Here - COMET 2011 - University of Oxford

Conference on molecular energy transferBook of abstractsDepartment of ChemistryandJesus CollegeUniversity of Oxford1

Plenary talks3

PLENARY TALK P1Collision studies with Stark-decelerated beamsGerard MeijerFritz-Haber-Institut der Max-Planck-Gesellschaft,Faradayweg 4-6, 14195 Berlin, Germanye-mail: meijer@fhi-berlin.mpg.deThe Stark-deceleration technique yields unprecedented control over both the internal and externaldegrees of freedom of polar molecules in a molecular beam. In comparison to conventionalmolecular beams, Stark-decelerated beams offer tunability of the velocity, a narrow velocity spread,and a high quantum state purity. We explore and exploit this new molecular beam technology invarious scattering experiments.In a crossed beam setup, Stark-decelerated OH radicals are scattered with all the rare gases as wellas with D 2 . The collision energy is varied from 70 to 800 cm -1 , and the behavior of the state-to-statescattering cross sections around the energetic thresholds is accurately determined. The study ofcollisions between two individual molecular species at a fully state-selected level is now alsopossible, as demonstrated in the crossed beam scattering of Stark-decelerated and state-selectedOH radicals with hexapole state-selected NO radicals. A merged beam experiment has been set upto reach collision energies in the 1 – 10 cm -1 range.A synchrotron for neutral polar molecules also offers interesting opportunities to study molecularcollisions. In a molecular synchrotron, bunches of molecules are confined in a potential well that hasa minimum along a circle. Synchrotrons allow for the confinement of multiple packets of moleculeswhich can repeatedly interact at well defined times and positions, thereby increasing the sensitivityfor detecting molecular collisions by orders of magnitude.In this presentation I will outline the operation principle of the various components that are used tomanipulate the motion of the molecules in the beam and I will give an overview of the possibilitiesthat this molecular beam technology presently offers. New developments in decelerator technology– including its integration on a chip – will be presented and future applications of this will bediscussed.4

PLENARY TALK P2Imaging studies of inelastic collisionsDavid H. ParkerDepartment of Molecular and Laser Physics, IMM, Radboud University, Nijmegen, the Netherlands.E‐mail address: parker@science.ru.nlState-to-state imaging studies of the interaction of small molecules including H 2 O, OH, CO andammonia with H 2 and with He will be described. These molecules are prominent components ofmolecular interstellar matter. In order to extract quantitative information on these molecules fromtelescope spectra, models are employed that depend critically on the rates of rotational energyexchange due to collisions with molecular hydrogen and helium. Collision rates are currentlydetermined by theory from the multidimensional Potential Energy Surface (PES) describing theinteraction of H 2 O and H 2 [1] or He [2] and OH with H 2 [3], or He. Our velocity map imaging [4]measurements of state-to-state differential and relative integral cross sections of rotational inelasticcollisions, also as a function of collision energy, are used to test these PESs. For the H 2 O/H 2 , Hesystem experiment is compared with state-of-the-art theoretical calculations by the group of L.Wiesenfeld (Grenoble) [5]. Our studies of astrochemistry relevant small molecules with the collisionpartners He and H 2 at collision energy relevant to that of the interstellar media should place thetheoretically determined PESs and the collision rates extracted from the PES on a firmer basis.References1. P. Valiron M. Wernli, A. Faure, L. Wiesenfeld, C. Rist, S. Kedžuch, J. Noga, J. Chem. Phys. 129 134306 (2008).2. J. Brudermann, C. Steinbach, U. Buck, K. Patkowski , R. Moszynski, J. Chem. Phys. 117 11166 (2002).3. A. R. Offer, M. C. van Hemert, J. Chem. Phys. 99 3836 (1993).4. A.T.J.B. Eppink, D. H. Parker, Rev. Sci. Instr. 68 3477 (1997).5. C.-H. Yang, G. Sarma, J.J. ter Meulen, D. H. Parker, G. C. Mc Bane, L. Wiesenfeld, A. Faure, Y. Scribano, N. Feautrier, J.Chem. Phys. 133, 131103 (2010).5

PLENARY TALK P3Roaming-mediated isomerization in the photodissociation of nitroaromaticsMichael L. Hause 1 , Nuradhika Herath 1 , Rongshun Zhu 2 , Ming-Chang Lin 2 ,and Arthur G. Suits 1, *1 Department of Chemistry, Wayne State University, Detroit, MI 48202.2 Department of Chemistry, Emory University, Atlanta, GA 30322Roaming reactions are a newly discovered class of unimolecular reaction in which a moleculeundergoes frustrated dissociation to radical products, followed by an intramolecular abstractionreaction. Nitro compounds have long been known to dissociate to give NO as a major product,assumed to form following isomerization to the nitrite. However, rates based upon isomerization viacalculated tight transition states are implausibly slow, thus the origin of this key dissociationpathway for an important class of molecules remains obscure. We present an imaging study of thephotodissociation of nitroaromatics with state-specific detection of the resulting NO products. Weobserve a bimodal translational energy distribution in which the slow products are formed with lowNO rotational excitation, while the fast component is associated with high rotational excitation.High-level ab initio calculations identified a “roaming-type” saddle point on the ground state, 1.3kcal/mol below the energy of separated C 6 H 5 + NO 2 . Branching ratio calculations show that thermaldissociation of nitrobenzene is dominated by “roaming-mediated isomerization” to phenyl nitrite,which rapidly decomposes to give C 6 H 5 O + NO._________________________*Corresponding author: asuits@chem.wayne.edu6

PLENARY TALK P4Ultrafast electronic dynamics in gas and liquid phasesstudied by time-resolved photoelectron spectroscopyToshinori SuzukiKyoto University, JapanWe studied non-adiabatic dynamics offundamental aromatic molecules such as pyrazineusing time-resolved photoelectron imaging withthe 22-fs time-resolution. Rapid changes of thephotoelectron energy and/or angular distributionclearly indicated the changes of the electroniccharacter during the dynamics. Time-resolvedphotoelectron spectroscopy has beam extendedto the liquid phase using a liquid beam. Thecharge transfer dynamics to solvent in an aqueoussolution is reported.References[1] “Probing ultrafast internal conversion throughconical intersection via time-energy map ofphotoelectron angular anisotropy”, J. Am. Chem. Soc.131, 10392 (2009).[2] "Time-resolved photoelectron imaging of ultrafast S 2 →S 1 internal conversion through conical intersection in pyrazine",J. Chem. Phys. 132, 174302 (2010).[3] "Molecular frame image restoration and partial wave analysis of photoionization dynamics of NO by time-energymapping of photoelectron angular distribution", Phys. Rev. Lett. 104, 073002 (2010).[4] "Direct measurement of vertical binding energy of a hydrated electron", Phys. Chem. Chem. Phys. 12, 3653 (2010).[5] "Direct measurement of vertical electron binding energies of solvated electrons in methanol and ethanol", Chem. Lett.39, 668 (2010).[5] "Isotope effect on ultrafast charge-transfer-to-solvent reaction from I - to water in aqueous NaI solution", ChemicalScience 2, 1094 (2011).7

PLENARY TALK P5Electronically nonadiabatic chemical dynamics at metal surfacesAlec M. WodtkeGeorg-August University of Göttingen and the Max Planck Institute for Biophysical Chemistry,Göttingen, GermanyDeveloping a predictive understanding of surface chemistry based on the first principles of Physicsmust include possible breakdown of the Born-Oppenheimer approximation. Reaching this goalmeans progressing beyond what is now possible for gas-phase bimolecular reactive encounters. Thisrepresents one of the most important challenges to current research in chemical physics; since, tothe extent that the Born-Oppenheimer approximation breaks down, we have no predictive theory ofsurface chemistry. This means we are working in an exciting environment where new phenomenamight be discovered through experiments and inspire new theoretical developments. This lecturewill present recent experimental results that demonstrate the importance of Born-Oppenheimerbreakdown. I will emphasize quantitative measurement that can be directly compared to dynamicaltheories that go beyond the Born-Oppenheimer Approximation.Related References[1] White, J.D., J. Chen, D. Matsiev, D.J. Auerbach, and A.M. Wodtke, Nature, 2005. 433(7025): 503-505.[2] Huang, Y.H., C.T. Rettner, D.J. Auerbach, and A.M. Wodtke, Science, 2000. 290(5489): 111-114.[3] Cooper, R., I. Rahinov, Z.S. Li, D. Matsiev, D.J. Auerbach, and A.M. Wodtke, Chemical Science, 2010. 1(1): 55-61.[4] Shenvi, N., S. Roy, and J.C. Tully, Science, 2009. 326(5954): 829-832.[5] Larue, J., T. Schafer, D. Matsiev, L. Velarde, N.H. Nahler, D.J. Auerbach, and A.M. Wodtke, Physical Chemistry ChemicalPhysics, 2011. 13(1): 97-99.8

PLENARY TALK P7Plans for preparing M-entangled moleculesNandini Mukherjee and Richard N. ZareDepartment of Chemistry, Stanford University, Stanford, CaliforniaContrary to the classical J distribution determined only by the M-state populations, here we haveplans to prepare a quantum mechanical ensemble whose distribution is determined by the relativephase of the magnetic M sublevels. The implication of M-entanglement in molecular polarization canbe understood in the following way. Consider, for example, the (v, J, M) levels of a rigid rotor. Thespatial distribution of the rigid rotor axes can be described per unit solid angle byJ2 2 * *( , ) |M| |JM( , ) | N M JM( , ) JN( , )M J M N (1)f C Y C C Y Y*where CMCNis the ensemble averaged correlation, also called the Zeeman coherence, of theM-state amplitudes, and YJM( , )is a spherical harmonic. Note that in the absence of any phasecorrelations between the interfering Zeeman amplitudes, the ensemble averagedfor M N.In the absence of Zeeman coherence the uniform M-state population impliesC CM*N 02| C M|being independent of M. The situation corresponds to an almost spherically symmetric distributionof the rigid rotor axis defined per unit solid angle element, which is given byJ2| YJM( , ) | 1M J .In the presence of Zeeman coherence, the molecular polarization, however, can arise from thepresence of the nonzero interference term, the second term on the right hand side of Eq. (1) whichis proportional to the cross termC CN*M. By using combined π and σ transitions in exciting atransition, the Zeeman coherence is injected in the final (v, J, M) levels. The M-entanglementensures that spatial confinement can be achieved simultaneously with nearly complete populationtransfer using adiabatic Raman passage. Several possible experiments will be described that canachieve M-state entanglement, primarily for the purpose of stereodynamical collision studies. M-state entanglement breaks the need to carry out M-state averaging over the collision process.Support from the U.S. Army Research Office is gratefully acknowledged.10

PLENARY TALK P8Unfolding the polarization-dependent differential cross sectionsin the reaction of Cl + CHD 3 (v 1 =1)Kopin LiuInstitute of Atomic and Molecular Sciences (IAMS),Academia Sinica, P. O. Box 23-166, Taipei, Taiwan 10617This talk will highlight our recent studies on the reaction of atoms/radicals with methaneisotopomers. The experiments were performed under crossed-beam conditions, using a time-sliced,ion velocity-imaging detection scheme, which enables us to acquire the quantum-state correlation ofthe coincidently formed product pairs [1, 2]. Such product pair-correlation measurements can revealdynamics information that are often hidden or lost by conventional measurements [3]. To explorethe mode-specific and bond-selective reactivity, a narrowband IR OPO/OPA was used to prepare thestretch-excited methane reactants [4-8]. A number of fundamental issues in reaction dynamics willbe elucidated when compared to the ground state reactivity. More recently, the polarizationproperty of the IR pumping laser was exploited to investigate the stereodynamical aspects ofreactive encounter in stretch-excited reactions [9]. We will demonstrate in this polarizationexperiment how to unfold a set of polarization-dependent differential cross sections from theimages acquired at various experimental geometries. The decoded polarization-dependentdifferential cross sections provide deeper insights into the stereo-specific reactivity.References[1] J. J. Lin, J. Zhou, W. Shiu, K. Liu, Rev. Sci. Instrum. 74, 2495-2500 (2003).[2] J. J. Lin, J. Zhou, W. Shiu, K. Liu, Science 300, 966-969 (2003).[3] K. Liu, Phys. Chem. Chem. Phys. 9, 17-30 (2007).[4] S. Yan, Y.-T. Wu, K, Liu, Science 316, 1723-1726 (2007).[5] J. Riedel, Y. Yan, H. Kawamata, K. Liu, Rev. Sci. Instrum. 79, 033105 (2008).[6] S. Yan, Y.-T. Wu, K, Liu, PNAS 105, 12667-12672 (2008).[7] W. Zhang, H. Kawamata, K. Liu, Science 325, 303 (2009).[8] F. Wang, K. Liu, Chem. Science 1, 126-133 (2010).[9] F. Wang, J.-S. Lin, K. Liu, Science 331, 900-903 (2011).11

PLENARY TALK P9How nature harvests solar lightRienk van GrondelleFaculty of Sciences, VU University, De Boelelaan 1081, 1081HV, Amsterdam, The NetherlandsThe success of photosynthesis relies on two ultrafast processes: excitation energy transfer in thelight-harvesting antenna followed by charge separation in the reaction centre. Both processes occurwith a quantum efficiency close to one, the natural system is highly adaptable, and self-protected.Crystal structure of a variety of light-harvesting complexes have become available over the last 15years and many have been studied in great detail using ultrafast lasers and other advancedspectroscopic techniques. In this talk I will illustrate which ‘design’ lessons we have learned fromnature that could inspire engineers in the construction of physical-chemical analogues.12

PLENARY TALK P10The chemistry of peptide sequencing elucidated by IR spectroscopyJos OomensFELIX facility, FOM Rijnhuizen / HIMS, University of AmsterdamWhile peptide sequencing by collision induced dissociation tandem mass spectrometry (CID MS) hasfound wide application in biochemistry, the underlying reaction chemistry remains an issue of livelydebate. The molecular structures of CID fragment ions form important, experimentally accessible,beacons on the reaction paths. In recent years, the application of infrared (IR) spectroscopy to CIDfragment ions of protonated peptides has provided important new information on these fragmention structures. While b-type ions are generally assumed to have an oxazolone structure and a-ions tohave an imine-type structure, IR spectra have indicated that various alternative structures occur aswell.Here we present infrared spectra of various peptide CID fragments in both positive and negative ionmode. New evidence for alternative structures is also found here. In addition, the spectra locateprotonation and deprotonation sites and reveal subtle influences of specific residues in thesequence on fragment structures formed.13

PLENARY TALK P11Time-resolved studies of vibrational relaxation and isomerizationin liquids and cryogenic matricesT. J. Preston 1 , Scott A. Reid 2 , and F. F. Crim 11 University of Wisconsin - Madison, Madison, Wisconsin 53706 USA2 Marquette University, Milwaukee, Wisconsin 53201 USATime-resolved spectroscopy makes it possible to follow directly the flow of energy within a moleculeand into the surrounding solvent, processes that can occur in as little as a few ps. It is also possibleto observe the photolytic production and relaxation of unusual species using similar approaches. Forexample, photodissociation and recombination of haloalkanes in solution can produce a relativelyweakly bound isomer, formed by the return of the departing halogen atom to bind to anotherhalogen atom in the radical fragment rather than to the carbon from which it departed. The 266-nmphotolysis of neat bromoform (HCBr 3 ) produces vibrationally excited isobromoform (HCBr 2 -Br),which can dissociate to release Br atoms into solution.Now it is possible to follow such an isomerization in the rather different environment of a cryogenicmatrix. Building on spectroscopy of such isomers in Ar matrices, we have photolyzedchloroiodomethane (H 2 CICl) and observed the time evolution of the iso-compound, H 2 CCl-I, formedby the caging and return of the departing I. A key to these experiments is using a separate pulse toconvert the product back to reactant after each excitation pulse. The time-evolution observed indifferent portions of the electronic absorption band of the isomer suggests that the first collision ofthe atom with the cage transfers substantial amounts of energy and that the partially relaxed isomerloses its remaining vibrational energy in about 30 ps. Comparing these results to studies in solutionshows that the formation and relaxation dynamics are relatively insensitive to the nature of thesurrounds.14

PLENARY TALK P12Energy transfer dynamics at the gas-liquid and gas-solidinterfaces: A quantum state resolved perspectiveMike Ziemkiewicz, Amelia Zutz, Joseph R. Roscioli, Dan Nelson, Andrew Gisler, andDavid J. NesbittJILA, University of Colorado and National Institute of Standards and Technology, andDepartment of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado803 09-0440Time permitting, this talk will present recent results from series of studies in our group on nonequilibriumcollision dynamics at the gas-liquid and gas-solid interface, invoking a suite ofIR/visible/UV laser based approaches. 1) Supersonically cooled molecules in skimmed jets are used tocollide with room temperature ionic liquid (RTILs) surfaces in vacuum, exploiting high resolutiondiode and IR quantum cascade laser Dopplerimetry to probe the rovibrational/translational states ofthe recoiling projectiles. 2) Scattering of open shell species (e.g., NO) from molten metals or moltensalts (e.g., Ga, RTILs) is explored as a function of incident beam energy and temperature, whichhighlight i) electronically non- adiabatic energy transfer and ii) electron-hole pair dynamics at thegas-liquid conductor interface. 3) Hyperthermal collision dynamics is explored at gas-liquid mimeticinterfaces such as self assembled monolayers (SAMs) on Au (111)/mica surfaces, using REMPI andvelocity map imaging to obtain a fully correlated quantum state and vector momentummap of the collision dynamics.15

PLENARY TALK P13Ultrafast x-ray science: applications to femto and atto chemistryDaniel M. NeumarkDepartment of Chemistry, University of California, Berkeley, CA 94720, USARecent developments in accelerator- and laser-based light sources have opened up new frontiers inchemical dynamics in which time-resolved experiments initiated by soft x-ray excitation can becarried out with femtosecond and even attosecond resolution. In this talk, experiments will bedescribed in which laser-based femtosecond and attosecond sources are used to probe dynamics inHe droplets and small molecules, respectively.16

PLENARY TALK P14Laser induced molecular imagingPaul CorkumJoint Attosecond Science Laboratory,University of Ottawa and National Research Council of CanadaOttawa, CanadaThe highly nonlinear interaction between intense few-cycle pulses and matter has led to newspectroscopic methods for probing molecules and their dynamics. For example: (1) Tunnellingaccurately describes ionization in intense infrared light pulses. I will show that measuring the angledependent ionization probability of a molecule is analogous to measuring the position dependenttunnelling rate on a surface with an STM [1]. (2) In moderate density gases, high harmonics of theinfrared pulse are produced. Technologically this has led to table-top soft X-ray sources that can beas short as 100 attoseconds. From a molecular perspective high harmonic spectroscopy is similarphotoelectron spectroscopy but with coherence and in reverse. I will show how high harmonicspectroscopy can be used to follow molecular dissociation of Br 2 [2] and to probe features ofasymmetric molecules such as CO [3].References[1] H. Akagi et al, Science 325, 1364 (2009)[2] H. Worner et al, Nature 466, 603 (2010)[3] E. Frumker et al, unpublished results17

PLENARY TALK P15Polar molecular gas in the quantum regimeDeborah Jin and Jun YeJILA, National Institute of Standards and Technology and University of Colorado,440 UCB, Boulder CO 80309-0440 USAMolecules at ultralow temperatures represent an exciting new frontier for atomic, molecular, andoptical physics that is endowed with a strong interdisciplinary character and connections to otherscientific fields, including chemistry, quantum information, and condensed matter physics. Theseconnections, and many possibilities for technological advances, arise naturally, as moleculesconstitute the ubiquitous building blocks of materials and embody common drives for everydayenergy-flow and dynamics. Control of molecular interactions has thus been an outstanding scientificquest for generations.Reaching the ultracold regime with molecules has long been hindered by the complex energy levelstructure of molecules, but the situation is now changing rapidly. Our recent experiment has broughtmolecules into the quantum regime, in which interaction dynamics must be described fully quantummechanically. We will present the first set of experiments that demonstrate ultracold molecularcollisions and chemical reactions where collisions must be described in terms of quantum wavefunctions. We can control the reaction rate using quantum statistics of the molecules. Long-rangeand anisotropic dipolar interactions have been observed in the thermodynamics of the moleculargas. Further, molecules can be confined in reduced spatial dimensions and the inelastic and elasticcollision rates can be precisely manipulated via an external electric field. Those efforts serve as animportant staging ground for the next step of exploring collective quantum effects in an ultracoldgas of molecules.18

Invited talks19

INVITED TALK I1Collision-induced alignment of NO(A 2 Σ + )Jeffrey J. Kay, (1) Mikhail Lemeshko, (2) Jacek Klos, (3) Grant Paterson, (4) Jeffrey D. Steill, (1) ElisabethWade, (5) Matthew L. Costen, (3) Kevin E. Strecker, (1) Kenneth G. McKendrick, (4)1 M. H. Alexander, (3)2 B.Friedrich, (2)3 and David W. Chandler (1)4(1)Sandia National Laboratories, Livermore, CA 94550, USA(2) Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany(3) Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA(4) School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK(5) Department of Chemistry and Physics, Mills College, Oakland, CA 94613, USAWe report the results of a joint experimental-theoretical investigation of collision-induced alignmentof NO in its first electronically-excited state (A 2 Σ + ). We measure alignment of NO(A 2 Σ + ) moleculesfollowing single collisions with argon and neon atoms by crossed-beam scattering combined withvelocity-mapped ion imaging. The images obtained in the experiment provide a direct measure of( 2)( 2)( 2)( 2)the and alignment moments. We calculate the and alignment moments for theA0 +A2 +NO(A 2 Σ + )/Ne system using three models of varying complexity: (i) a classical hard-shell model, (ii) aFaunhofer quantum diffraction model, and (iii) quantum scattering calculations with an ab initioelectronic potential energy surface. The experimental results match the ab initio calculations mostclosely and indicate that, unlike scattering in the X 2 Π 1/2 ground state, the collision stereodynamicsare not adequately captured by hard-shell scattering or Fraunhofer diffraction, and are stronglyaffected by longer-range forces. This appears to be the result of the more diffuse and much softer3sσ orbital occupied by the outer unpaired electron in the A 2 Σ + state of NO.A0 +A2 +1 k.g.mckendrick@hw.ac.uk2 mha@umd.edu3 brich@fhi-berlin.mpg.de4 chand@sandia.gov20

INVITED TALK I2Theoretical investigation of rotationally inelasticcollisions of molecular free radicalsPaul J. Dagdigian* and Qianli MaDepartment of Chemistry, The Johns Hopkins University, Baltimore,MD 21218 -2685, USAMillard H. Alexander and Lifang MaDepartment of Chemistry and Biochemistry, University of Maryland, College Park,MD 20742-2021, USASeveral topics in rotationally inelastic collisions of diatomic and small polyatomic molecular freeradicals with atomic collision partners will be addressed. Resonances in rotationally inelasticcollisions should be very sensitive to the features of the PES. These features arise at low collisionenergies, due to decay of quasibound van der Waals levels behind centrifugal barriers, andthresholds to formation of higher rotational levels, from Feshbach resonances. Calculations onseveral exemplary systems will be presented to illustrate the properties of these resonances andtheir dependence on the rotational levels involved.In addition to the collisional loss and transfer of population, it is also of interest to investigate theanalogous loss and transfer of polarization (e.g. orientation and alignment). Calculations on theelastic depolarization and collisional transfer of polarization in collisions of CN(A 2 Π) with Ar will bepresented. These results will be compared with experimental measurements by McKendrick, Costen,and co-workers.If time permits, collisions of the polyatomic radical methyl will be discussed. Quantum scatteringcalculations of collisions with the helium atom have been carried out, based on a computedRCCSD(T) potential energy surface (PES). There are two types of anisotropies in a PES involving apolyatomic molecule, unlike the case of a diatomic molecule; these can be described as anisotropieswithin the molecular plane and above/below the plane. The anisotropy of the interaction of CH 3 ofwith helium is dominated by the former, because the repulsion between the hydrogen atoms andhelium. This anisotropy is found to affect dramatically the rotational energy transfer cross sectionsand rate constants for this system.*pjdagdigian@jhu.edu21

INVITED TALK I3Photodissociation of N 2 O: A comprehensive dynamics studyReinhard SchinkeMPI for Dynamics and Self-Organization, Göttingen, GermanyA comprehensive theoretical study of the photodissociation of N 2 O will be presented. The basis arenew three-dimensional potential energy surfaces (PES) for the ground state 1 1 A’ (X) and the firstexcited state of the same symmetry, 2 1 A’ (A). They were calculated at the MRCI level of theory withwave functions obtained by full valence CASSCF calculations and using the aug-cc-pVQZ basis set.Absorption spectra for several initial vibrational states were calculated by exact wave packetpropagation on the A PES. In addition, one- and two state classical trajectory calculations wereperformed. The absorption spectrum, including its temperature and isotope dependence, is wellreproduced by the calculations. The diffuse vibrational structures are well described and explained interms of wide-amplitude bending and NN stretching periodic orbits. The N 2 fragment is produced inextremely high rotational states, in agreement with experimental results. The degree of vibrationalexcitation rises strongly with photon energy. Also the β parameter describing the product angulardistribution is well reproduced, including the strong dependence on the rotational state. Nonadiabatictransitions from state A to X at intermediate separations were found to be important. Finally,the quantum yield of O( 3 P) was calculated in two-state wave packet calculations including spinorbitcoupling. The value of about 0.2% agrees satisfactorily with the experimental value of 0.5±0.2%.In summary, the photodissociation of N 2 O in the 180 nm band is understood. Only the 2 1 A’ stateappears to be involved whereas other states, for example 1 1 A’, appear to be unimportant.22

INVITED TALK I4Spectroscopy and dynamics of the HOCO and DOCO radicalsC.J. Johnson, 1 B.L.J. Poad, 2 B.B. Shen 2 and R.E. Continetti 21 Department of Physics, University of California, San Diego, USA2 Department of Chemistry and Biochemistry, University of California, San Diego, USAThe HOCO radical plays a crucial role in the reaction of OH + CO → H + CO 2 , yet significant questionsregarding the detailed dynamics of this reactive intermediate remain. Through photoelectron andphotoelectron-photofragment coincidence spectroscopy on cold HOCO¯ and DOCO¯ anions, we havegained new insight into the dynamics of the strongly bound HOCO system. The experiments reportedin this work make use of a cryogenic electrostatic ion beam trap, [1] and represent a significantimprovement over our earlier studies of this system where internally excited HOCO¯ anions hindereda straightforward interpretation of the experimental results.[2],[3] We have extended these studiesto include the deuterated DOCO isotopologue at a wide range of wavelengths. Near-thresholdphotoelectron studies of the two isotopologues reveal structured spectra that characterize the HOCOradical well, and have allowed for a reassignment of the electron affinities for both cis- and transisomers.At higher photon energies excited HOCO/DOCO radicals are produced that undergotunneling to H + CO 2 /D + CO 2 as well as dissociation to the OH + CO/OD + CO entrance channel.[4]The new data allows energy-resolved tunneling lifetimes in the microsecond range to be inverted toobtain a model barrier to formation of H + CO 2 that is consistent with experimental internal energydistributions. The observed tunneling lifetimes at the top of the barrier confirm that tunneling playsan important role in this elementary combustion reaction. This work supported by the USDepartment of Energy under grant number DE-FG03-98ER14879References[1] C.J. Johnson and R.E. Continetti, J. Phys. Chem. Lett. 1 (2010) 062007.[2] T.G. Clements, R.E. Continetti and J.S. Francisco, J. Chem. Phys. 117 (2002) 6478.[3] Z. Lu, Q. Hu, J.E. Oakman and R.E. Continetti, J. Chem. Phys. 127 (2007) 194305.[4] C.J. Johnson, B.L.J. Poad, B.B. Shen and R.E. Continetti, J. Chem. Phys. 134, 171106 (2011).23

INVITED TALK I8Experimental investigations of radical-molecule reactions using lowtemperature supersonic flows and applications to atmospheric andastrophysical chemistryIan R. Sims*Institut de Physique de Rennes, UMR 6251 du CNRS – Université de Rennes 1, Equipe AstrochimieExpérimentale, Bat. 11c, Campus de Beaulieu, 35042 RENNES Cedex, France.The use of the CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme, or ReactionKinetics in Uniform Supersonic Flow) technique coupled with pulsed laser photochemical kineticsmethods has revolutionised the field of low temperature kinetics in the gas phase. Radical-radical,radical-unsaturated molecule and even radical-saturated molecule reactions have been shown to berapid down to the temperatures of dense interstellar clouds (10—20 K), and the results have had amajor impact in astrochemistry and planetology, as well as proving an exacting test for theory. 1I will briefly describe the technique and give details of recent technical developments that haveenabled us to undertake three studies of fundamental interest, with applications for bothastrophysical and atmospheric chemistry:2 The formation kinetics and stability of HO 3 Atom-H 2 reactions at very low temperatures 3 Low temperature formation of cyanopolyynesReferences[1] H. Sabbah, L. Biennier, I. R. Sims, Y. Georgievskii, S. J. Klippenstein, and I. W. M. Smith, Understanding reactivity at verylow temperatures: The reactions of oxygen atoms with alkenes, Science 317 (2007), 102-105.[2] S. D. Le Picard, M. Tizniti, A. Canosa, I. R. Sims, and I. W. M. Smith, The Thermodynamics of the Elusive HO 3 Radical,Science 328 (2010), 1258-1262.[3] C. Berteloite, M. Lara, A. Bergeat, S. D. Le Picard, F. Dayou, K. M. Hickson, A. Canosa, C. Naulin, J. M. Launay, I. R. Sims,and M. Costes, Kinetics and Dynamics of the S( 1 D 2 ) + H 2 SH + H Reaction at Very Low Temperatures and CollisionEnergies, Phys. Rev. Lett. 105 (2010), 203201.*email : ian.sims@univ-rennes1.fr27

INVITED TALK I9Towards efficient dynamics: Observing and controllingconical intersection dynamics in retinalsMatz Liebel 1 , Giovanni Bassolino 1 , Tina Sovdat 2 , Stephen Fletcher 2 and Philipp Kukura 11 Department of Chemistry, The Physical and Theoretical Chemistry Laboratory, University of Oxford,South Parks Road, Oxford, OX1 3QZ, UK2 Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road,Oxford, OX1 3TA, UKThe first step in vision involves the 11-cis to all-trans isomerisation of the retinal chromophore in thevisual pigment rhodopsin. The reaction has been shown to be extremely fast (

INVITED TALK I10Conical intersections and their role for the photostability of thebuilding blocks of lifeWolfgang DomckeTechnical University, München, GermanyHigh stability with respect to photochemical destruction by ultraviolet light is a decisive property ofbiological molecules. Recent excited-state electronic-structure calculations and time-dependentquantum wave-packet calculations of the nuclear motion have revealed the role of conicalintersections of electronic potential-energy surfaces for the highly efficient excited-statedeactivation in biological molecules such as DNA bases, DNA base pairs, aromatic amino acids andpeptides. The twisting of CC double bonds or CN bonds in 1 ππ* excited states has been identified asa generic mechanism for ultrafast radiationless decay in heteroaromatic molecules. In addition,extensive experimental and computational studies have provided clear evidence of the role ofoptically dark and dissociative 1 πσ* states in the excited-state deactivation of aromaticchromophores with acidic groups (OH, NH, or NH 2 ). Our ab initio computational results indicate thatspecific electron-driven proton-transfer processes in hydrogen-bonded supramolecular systems alsoplay a universal role in the photochemistry of biopolymers (DNA and proteins). It is suggested thatthese processes are the origin of the exceptional photostability of these compounds which has leadto their selection at the very beginning of the biological evolution.29

INVITED TALK I11Taking the plunge: quantum state resolved dynamicsof chemical reactions in solutionA.J. Orr-Ewing, S.J. Greaves, R.A. Rose, F. Abou-Chahine, T.A.A. Oliver,M.N.R. Ashfold, D.R. Glowacki and J.N. HarveySchool of Chemistry, University of Bristol, Bristol BS8 1TS, UKM. Towrie, G.M. Greetham, I.P. Clark and A.W. ParkerCentral Laser Facility, Research Complex at Harwell, Didcot, Oxfordshire OX11 0QX, UKThe study of chemical reaction dynamics has greatly profited from experiments carried out ongaseous samples at very low pressure (e.g. using molecular beam methods) to ensure single-collisionconditions. Much important chemistry takes place in liquid environments, however, and questionstherefore arise about how a liquid solvent affects the dynamics of elementary reactions. We haveaddressed such questions by studying the vibrational quantum-state specific dynamics of reactionssuch asCN + c-C 6 H 12 HCN(v 1 v 2 v 3 ) + c-C 6 H 11 (1)in solution in organic solvents such as chloroform, dichloromethane and tetrahydrofuran [1-3].Ultrafast transient infra-red absorption spectroscopy with broadband IR probe pulses reveals thenascent excitation of the C-N stretching (v 1 ), bending (v 2 ) and C-H stretching (v 3 ) modes of the HCNproduct and the relaxation of this vibrational excitation by coupling to the solvent. Rich dynamicalbehaviour has been observed for reaction (1) and the equivalent reaction of CN radicals with c-C 6 D 12and is being interpreted with the aid of computer simulations of the chemistry under both isolatedgas-phase conditions and in solution in an organic solvent [4,5]. The experiments are now beingextended to H-abstraction reactions of Cl atoms with hydrocarbons to complement a large body ofstudies in the gas phase.References[1] S.J. Greaves, R.A. Rose, T.A.A. Oliver, D.R. Glowacki, M.N.R. Ashfold, J.N. Harvey, I.P. Clark, G.M. Greetham, A.W.Parker, M. Towrie and A.J. Orr-Ewing, Science, 331, 1423-1426 (2011)[2] A.J. Orr-Ewing, D.R. Glowacki, S.J. Greaves and R.A. Rose, J. Phys. Chem. Lett. 2, 1139-1144 (2011)[3] R.A. Rose, S.J. Greaves, T.A.A. Oliver, I.P. Clark, G.M. Greetham, A.W. Parker, M. Towrie, and A.J. Orr-Ewing, J. Chem.Phys. 134, 244503 (2011)[4] D.R. Glowacki, A.J. Orr-Ewing and J.N. Harvey, J. Chem. Phys. 134, 314508 (2011)[5] D.R. Glowacki, R.A. Rose, S.J. Greaves, A.J. Orr-Ewing and J.N. Harvey, accepted for publication (August 2011).30

INVITED TALK I12Gas phase and gas surface reaction dynamics studiesGeorge C. SchatzNorthwestern University, USAThis talk will describe our recent studies of hyperthermal atomic oxygen reacting with gas phasemolecules, with hydrocarbon liquids, with ionic liquids and with diamond. In these studies, the highenergies shorten the time-scale of the dynamics to the few ps range, and this makes it possible touse molecular dynamics methods within a QM/MM framework to directly simulate the reactivedynamics. I show how these theoretical methods can be used to understand primary reactionmechanisms, as well as angular and energy distributions of the gaseous products. Related studies ofsodium atoms at water and glycerol surfaces will be described.31

INVITED TALK I13Trapping and characterization of reaction intermediatesusing cryogenic ion chemistryMark A. JohnsonYale University, USAComplex, non-covalent interactions between small molecules and biopolymers mediate manychemical processes in signalling, antibiotic action, and site-selective catalysis. Identification of thelocal attachment motifs is quite difficult, however, because the host-guest complexes are oftentransient, fluxional species that are not amenable to structural analysis with traditional methods (xray,nmr, etc). We demonstrate how vibrational spectroscopy can provide this information directlythrough the frequency changes induced in covalent bonds that are effectively touching at thecontact points. The information becomes possible because of the narrow intrinsic vibrational bandsthat are obtained when species are extracted from solution, frozen near 10K in the gas phase, andmeasured using mass-selective predissociation of weakly bound H 2 molecules. Resonances closelyassociated with individual oscillators embedded within a catalyst-substrate complex are easilyidentified through extensive use of site-specific isotope labelling. Analysis of these patterns thenyields a microscopic picture of the docking configuration.32

INVITED TALK I14Dynamics of gas-liquid interfacial scatteringKenneth G. McKendrickSchool of Engineering and Physical Sciences, Heriot-Watt University, UKRecent progress on the experimental investigation of the dynamics of gas-liquid interfacial collisionsis described. We have developed a method based on laser-photolytic generation of gas-phaseprojectiles and laser-induced fluorescence (LIF) detection of the nascent products scattered backinto the gas phase. Its application to a number of related systems will be described. These includecollisions of OH radicals with a range of functionalised organic liquids. The dynamics of the inelasticscattering of the OH and the dependence of its survival probability (and by implication, its loss viareactive uptake) on the functional groups present in the liquid are determined. We consider theimplications for the ageing of the surfaces of atmospheric aerosols. The reaction of electronicallyexcited O(1D) atoms with the benchmark liquid alkane, squalane, has also been studied. We contrastthe dynamics of OH product formation with those of the analogous O( 3 P) reaction.33

INVITED TALK I15Steric effects and vibrational bond selectivity in the dissociativechemisorption of methaneRainer D. BeckLaboratoire de Chimie Physique MoléculaireEcole Polytechnique Fédérale de Lausanne, Switzerland.We describe recent state-resolved gas/surface reaction dynamics experiments probing steric effectsand vibrational bond selectivity in the dissociative chemisorption of methane on Ni and Pt surfaces.Steric effects in the dissociation of vibrationally excited methane on Ni single crystal surfaces wereexplored for the first time by aligning surface incident methane in a molecular beam by linearlypolarized infrared excitation of the C-H stretch mode of two methane isotopologues (CH 4 (n 3 ) andCD 3 H(n 1 )). An increase in methane reactivity of as much as 100% is observed when the laserpolarization direction is changed from normal to parallel to the surface plane. The dependence ofthe alignment effect on the rotational branch used for excitation (P, Q, or R-branch) indicates thatthe alignment of the C-H stretch amplitude rather than the angular momentum is responsible for thesteric effect [1]. The results demonstrate specific steric requirements for this benchmark gas/surfacereaction and will serve as a stringent test of multi-dimensional dynamics calculations.Reflection absorption infrared spectroscopy (RAIRS) was used to probe for vibrational bondselectivity in the chemisorption of three partially deuterated methane isotopologues. While incidentkinetic energy and/or thermal vibrational excitation produce a nearly statistical distribution of C-Hand C-D bond cleavage products in methane chemisorption on Pt(111), selective laser excitation ofan infrared active C-H stretch normal mode was found to lead to highly selective dissociation of a C-H bond for any of the three isotopologues CHD 3 , CH 2 D 2 , CH 3 D. This indicates that surface-inducedIVR during the approach of the vibrationally excited molecules to the metal surface is either absentor very limited. Our results show that the concept of vibrational state-controlled chemistry is notlimited to bi-molecular reactions in the gas phase but can be applied successfully to directdissociative chemisorption reactions of a gas phase molecule on a metallic surface.References[1] B.L. Yoder, R. Bisson, and R.D. Beck, Science 329, 553 (2010).34

INVITED TALK I16Towards Polanyi rules for polyatomics via time-resolvedphotoelectron spectroscopyAlbert StolowNRC, Ottawa, CanadaThe conical intersection plays a role in excited state reaction dynamics very similar to that of thetransition state in ground state dynamics. As such, one might hope that there should emerge, forexcited state polyatomic dynamics, a set of notions analogous to the Polanyi rules for ground stateswhich guide our thinking about the topography and location of conical intersections relative topotential gradients, barriers and thresholds. Will there be notions such as "early" or "late"? Do the"velocity" and "direction" of passage through a conical intersection affect diabatic versus adiabaticbranching? We begin with a phenomenological approach by using the location and number ofmethyl substituents on unsaturated hydrocarbons as a "variable" to tune trajectory motions nearconical intersections. We experimentally probe the fast excited state dynamics using time-resolvedphotoelectron spectroscopy, a method sensitive to both vibrational and electronic degrees offreedom.35

INVITED TALK I17Femtosecond dynamics through conical intersectionsRussell Minns, Dorian Parker, Roman Spesyvtsev, Oliver Kirkby,Morgane Vacher and Helen FieldingDepartment of Chemistry, University College London,20 Gordon Street, London WC1H 0AJ, UKUltrafast relaxation of electronically excited states through conical intersections plays a key role inmany photochemical and photobiological processes. Time-resolved photoelectron spectroscopy hasemerged as an extremely valuable tool for following such non-adiabatic processes. However,unravelling vibrationally-unresolved, femtosecond photoelectron spectra, is challenging. We presenttime-resolved photoelectron spectra that enable us to gain deeper insight into the excited statedynamics of benzene [1] and aniline [2].In benzene, we excite the lowest electronically excited singlet state at 243 nm, close to the onset of“channel 3”. Using different probe energies to record the total photoelectron yield as a function ofpump-probe delay we reveal that S 1 , T 1 and T 2 electronic states are involved in the excited statedynamics. Time-resolved photoelectron spectroscopy measurements then allow us to unravel theevolution of the S 1 , T 1 and T 2 components of the excited state population which, together withcomplementary quantum chemistry and quantum dynamics calculations, show that ultrafastintersystem crossing competes with internal conversionIn aniline, we excite the optically bright S 3 (*) state at 236 nm. The S 1 (*) and S 3 (*) statesappear in the photoelectron spectra as broad bands with some vibrational resolution, allowing us toidentify some of the modes involved in the electronic relaxation. The Rydberg nature of the opticallydark S 2 (*) state in the Franck-Condon region is visible in the photoelectron spectra as a narrowpeak with angular anisotropy. The resolution of the electronic states in the photoelectron spectraallows us to determine timescales for S 3 – S 1 , S 3 – S 2 , S 2 – S 1 and S 1 – S 0 internal conversion and todetermine the role of the * dissociative state in the relaxation dynamics.AcknowledgmentsThis work was supported by the EPSRC, The Ramsay Trust and the European Marie Curie InitialTraining Network Grant No. CA-ITN-214962-FASTQUAST. We gratefully acknowledge ourcollaborations and valuable discussions with Tom Penfold and Graham Worth.References[1] R.S. Minns, D.S.N. Parker, T.J. Penfold, G.A. Worth and H.H. Fielding, PCCP 12 15607 (2010)[2] R. Spesyvtsev, O.M. Kirkby, M. Vacher and H.H. Fielding, In preparation (2011)36

INVITED TALK I18Improved measurement of the electron electric dipole momentEdward A. HindsCentre for Cold Matter, Blackett Laboratory,Imperial College London, Prince Consort Road,London SW7 2AZ, United Kingdom.The electron’s charge distribution can be characterised by its electric dipole moment (EDM), d e ,which measures the deviation of its electric interactions from purely spherical. According to thestandard model, this EDM is d e ≈ 10 -38 e. cm – some eleven orders of magnitude below the currentexperimental limit. However, most extensions to the standard model predict much larger values,potentially accessible to measurement. 1 Hence, the search for the electron EDM is a search forphysics beyond the standard model. Moreover, a non-zero d e breaks time-reversal symmetry which,in many models of particle physics, is equivalent to breaking the symmetry between matter andantimatter, known as CP symmetry. New CP-breaking physics is thought to be needed to explain theexistence of a material universe 2 . We have used a supersonic beam of cold YbF molecules to measurethe electron EDM, obtaining the result d e = (–2.4 ± 5.7 stat ± 1.5 syst ) x 10 -28 e. cm and setting a newupper limit of |d e | < 10.5 x 10 -28 e. cm with 90% confidence. 3 Our result, consistent with zero,indicates that the electron is spherical at this improved level of precision. Our measurement, of attoeVenergy shifts in a molecule, probes new physics at the tera-eV energy scale. Many extensions tothe standard model, such as the minimal supersymmetric standard model, naturally predict largeEDMs and our measurement places significant constraints on the parameters of these theories. 4References1 E. D. Commins, Electric dipole moments of leptons, in Advances in Atomic, Molecular, and Optical Physics, Vol. 40, B.Bederson and H.Walther (Eds.), Academic Press, New York, pp. 1-56 (1999).2 A. D. Sakharov, Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe, Pis’ma ZhETF 5, 32(1967). [Sov. Phys. JETP Lett. 5, 24 (1967).]3 J. J. Hudson, D. M. Kara, I. J. Smallman, B. E. Sauer, M. R. Tarbutt, E. A. Hinds “Improved measurement of the shape of theelectron”, Nature 473, 493 (2011). doi:10.1038/nature101044 E. D. Commins and D. DeMille, “The electric dipole moment of the electron”, Chapter 14 in Lepton Dipole Moments Eds.B. L. Roberts and W. J. Marciano, (World Scientific, Singapore 2010).37

Contributed talks39

CONTRIBUTED TALK C1A new spectroscopic window on hydroxyl radicals using UV+VUV resonant ionizationJoseph M. Beames, Fang Liu and Marsha I. LesterDepartment of Chemistry, University of Pennsylvania, Philadelphia PA 19104, USACraig MurraySchool of Chemistry, University of Bristol, Bristol BS8 1TS, UKThe hydroxyl radical (OH) plays a crucial role in atmospheric, interstellar and combustion chemistry.Accurate spectroscopic characterization of its electronic states and reaction dynamics are thereforevital, and has understandably received considerable attention. Predominantly these properties havebeen investigated using laser induced fluorescence methods, typically utilizing the A-X band.However, over the last few decades, significant developments in ionization techniques and ionmanipulation have proven such experiments to be invaluable in providing further information onmolecular reaction pathways and dynamics. This suggests that a sensitive state-selective ionizationscheme for OH is also needed. Several resonance enhanced multiphoton ionization (REMPI) schemeshave already been demonstrated (2+1, 3+1 and 1+1'), with each method employing high-lyingRydberg states as resonant intermediates before ionization. Only the 2+1 scheme has been used inany dynamical measurements of OH, despite weak ion signal intensities attributed to predissociationof the intermediate Rydberg state. We demonstrate a new 1+1’ REMPI scheme that utilizes the A 2 Σ +state as the resonant intermediate, before further promoting the OH radicals to an autoionizingRydberg series. The second step is initially performed using fixed frequency VUV from frequencytripling the 3 rd harmonic of a Nd:YAG laser. We show that the ionization cross section of OH A2 Σ + (v=1) at this wavelength is on the order of 10 -17 cm 2 , which illustrates the sensitivity of thistechnique. The feasibility of this approach, using readily available wavelengths and a wellcharacterizedresonant transition, suggests it will be widely applicable as a means of detecting OHradicals.40

CONTRIBUTED TALK C3Photochemistry of ClOOCl and formation of the ozone holeJim Jr-Min LinInstitute of Atomic and Molecular Sciences, Academia Sinica, Taipei, TaiwanE-mail: jimlin@gate.sinica.edu.twThe photochemistry of the ClO dimer (ClOOCl) plays a central role in catalytic destruction of polarstratospheric ozone [1-8]. In spite of intense investigations for decades, some of its laboratoryphotochemical data had not reached the desired accuracy to allow a reliable simulation of thestratospheric ozone loss until recently. Inevitable impurities in ClOOCl samples have obstructedconventional measurements. In particular, an absorption measurement of ClOOCl in 2007 [3] whichgave much lower cross sections than previous studies implied that the formation of Ozone Holecannot be explained with current chemical models. Scientists were wondering if the model isinsufficient or the data is erroneous [1,2]. Efforts [4-8] aiming to resolve this controversy will begiven in this presentation, emphasizing newly developed experiments to determine two criticalphotochemical properties of ClOOCl - its absorption cross section and product branching ratio.References:[1] M. von Hobe, Revisiting ozone depletion, Science, 318, 1878 (2007).[2] Q. Schiermeier, Chemists poke holes in ozone theory, Nature, 449, 382 (2007).[3] F. D. Pope, J. C. Hansen, K. D. Bayes, R. R. Friedl, and S. P. Sander, Ultraviolet Absorption Spectrum of Chlorine Peroxide,ClOOCl, J. Phys. Chem. A 111, 4322 (2007).[4] H.-Y. Chen, C.-Y. Lien, W.-Y. Lin, Y. T. Lee, and J. J. Lin, UV Absorption Cross Sections of ClOOCl Are Consistent with OzoneDegradation Models, Science 324, 781 (2009).[5] C.-Y. Lien, W.-Y. Lin, H.-Y. Chen, W.-T. Huang, B. Jin, I-C. Chen, and J. J. Lin, Photodissociation cross sections of ClOOCl at248.4 and 266 nm, J. Chem. Phys. 131, 174301 (2009).[6] B. Jin, I-C. Chen, W.-T. Huang, C.-Y. Lien, N. Guchhait, and J. J. Lin, Photodissociation Cross Section of ClOOCl at 330 nm,J. Phys. Chem. A 114, 4791 (2010).[7] W.-T. Huang, A. F Chen, I-C. Chen, C.-H. Tsai and J. J. Lin, Photodissociation dynamics of ClOOCl at 248.4 and 308.4 nm,Phys. Chem. Chem. Phys., 13, 8195-8203 (2011).[8] J. J. Lin, A. F Chen, and Y. T. Lee, UV Photolysis of ClOOCl and Ozone Hole, Chem. Asian J. (Focus Review, 2011, DOI:10.1002/asia.201100151).42

CONTRIBUTED TALK C4Time-resolved predissociation of CH 3 I excited in the origin level of the B stateN. Thiré 1,2 , R.Cireasa 1,2 , D.Staedter 1,2 , S. T. Pratt 3 and V. Blanchet 1,21 Université Paul Sabatier, 118 route de Narbonne 31062 Toulouse, France2 CNRS, Laboratoire Collisions Agrégats Réactivité, IRSAMC, 31062 Toulouse, France3 Argonne National Laboratory, Argonne,IL 60439, USTime domain studies of the predissociation of Rydberg states of methyl iodide (CH 3 I) have primarilybeen performed by monitoring the decay of the parent ion signal produced by photoionization ofthe Rydberg states. Using this approach, the origin band of the optically active Rydberg state,namely the B 6s[2] state, was found to have a picosecond lifetime [1,2], while higher vibrationallevels of this state were found to have significantly shorter lifetimes [3-5]. Recently, we have studiedthe predissociation of the origin band of the B 6s[2] state by time-resolved photoelectronspectroscopy [6].Here the predissociation dynamics of the vibrationless level of the first Rydberg state 6s (B 2 2 E 3/2 ) ofCH 3 I has been studied by femtosecond-resolved velocity map imaging (fs-VMI) of both the CH 3 and Iphotofragments. The only channel detected is I* as already detected recently [7]. The kinetic energydistributions of the two fragments have been recorded as a function of the pump-probe delay, andas a function of excitation within the umbrella and stretching vibrational modes of the CH 3 fragment.These observations are made by using (2+1) Resonant Enhanced MultiPhoton Ionization (REMPI) viathe 3p 2 z A 2 ” state of CH 3 to detect specific vibrational levels of CH 3 . The vibrational branchingfractions of the CH 3 are recovered by using the individual vibrationally state- selected CH 3distributions to fit the full kinetic energy distribution obtained by using non-resonant multiphotonionization of either the I or CH 3 fragment. The angular distributions and rise times of the twofragments differ significantly. These observations can be rationalized through a consideration of thealignment of the CH3 fragment and the effect of this alignment on the detection efficiency of theCH 3 . Iodine shows as well a Rydberg fingerprint generated at (1+1’) in agreement with thephotoelectron spectrum.References[1] J. C. Owrutsky and A. P. Baronavski, Chem. Phys. Lett., 1994, 222, 335-338.[2] Z.-r. Wei et al, Chin. J. Chem. Phys., 2007, 20, 419-424.[3] A. P. Baronavski and J. C. Owrutsky, J. Chem. Phys., 1998, 108, 3445-3452.[4] A. H. Zewail and H. Guo, Can. J. Chem., 1994, 72, 947-957.[5] D. Zhong, P. Y. Cheng and A. Zewail, H. , J. Chem. Phys., 1996, 105, 7864-7867.[6] N. Thiré et al, Phys. Chem. Chem. Phys., 2010, 12 15644 - 15652.[7] G. Gitzinger et al, J. Chem. Phys., 2010, 132, 234313.43

CONTRIBUTED TALK C5Photochemistry of methanol on TiO 2 (110)Chuanyao Zhou 1 , Zefeng Ren 1 , Zhibo Ma 1 , Shijing Tan 2 , Hongjun Fan 1 , Bing Wang 2 , Xueming Yang 1*1. State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics,Chinese Academy of Science, Dalian, Liaoning Province, China.2. Hefei National Laboratory for Physical Sciences at the Microscale, University of Science andTechnology of China, Hefei, Anhui Province, China.Titanium dioxide is one of the most important materials for real world applications in chemicalcatalysis[1-4]. Photocatalysis by TiO 2 , especially its application in water splitting[1], has attractedmuch attention. It has been reported that pure TiO 2 is minimally active for water splitting to producehydrogen[5], while the same catalyst is much more active for hydrogen production from water–methanol mixture[6]. Clearly, the chemistry of methanol on TiO 2 has played a crucial role in thisprocess. Therefore, it is essential to understand the photocatalytic chemistry of methanol on TiO 2 ,which could potentially provide clues for developing new efficient photocatalysts for water splitting.Here, we report the first clear evidence of photocatalyzed splitting of methanol on TiO 2 derived fromtime-dependent two-photon photoemission (TD-2PPE) results in combination with scanningtunneling microscopy (STM). STM tip induced molecular manipulation before and after UV lightirradiation clearly reveals photocatalytic bond cleavage, which occurs only at Ti 4+ surface sites. TD-2PPE reveals that the kinetics of methanol photodissociation can be well described by the fractal-likekinetics model, however, the physical nature of the fractal parameters is not clear immediately.Further studies showed that the photocatalyzed dissociation rate of methanol on reduced TiO2(1 10)is more than an order of magnitude faster than on the stoichiometric surface, indicating the surfacedefects could accelerate the photocatalysis process of methanol on TiO2(110) in a significant way,probably by lowering the reaction barrier.[1] A. Fujishima and K. Honda, Nature, 1972, 238, 37.[2] M. A. Fox and M. T. Dulay, Chem. Rev., 1993, 93, 341.[3] P. V. Kamat, Chem. Rev., 1993, 93, 267.[4] A. L. Linsebigler, G. Lu and J. T. Yates, Jr, Chem. Rev., 1995, 95, 735.[5] S. Sato and J. M. White, Chem. Phys. Lett., 1980, 72, 83.[6] T. Kawai and T. Sakata, J. Chem. Soc., Chem. Commun., 1980, 694.Corresponding Author: Prof. Xueming Yang, xmyang@dicp.ac.cn44

CONTRIBUTED TALK C6Quasi-classical trajectory-Gaussian binning study of OH + D 2 → HOD(v 1 ’,v 2 ’,v 3 ’) + Dangle-velocity and vibrational distributions at 0.28 eV andinfluence of vibrational excitation of reactantsJosé Daniel Sierra, 1 Laurent Bonnet 2 and Miguel González 31 Departamento de Quimica, Universidad de La Rioja, Spain2 Institut des Sciences Moléculaires, Université Bordeaux I, France3 Departament de Quimica Fisica i IQTC, Universitat de Barcelona, SpainThe OH + H 2 → H 2 O + H reaction is a benchmark tetratomic reaction, as advanced electronicstructure and dynamics calculations are feasible, thus allowing a high level comparison betweentheory and experiment [1] (the isovalent F + H 2 plays a similar role for triatomic reactions). Aparticularly remarkable experimental result on the OH + D 2 → HOD + D isotopomer reaction is theangle-velocity distribution at a collision energy (ET) of 0.28 eV, which presents several sharp peaksrelated with the HOD vibrational levels (0,0,2), (0,1,1), (0,0,1) and (0,0,0), where v 1 ’, v 2 ’, and v 3 ’ referto the quantum numbers for the O-H stretching, H-O-D bending, and O-D stretching, respectively [2].Earlier crossed beam experiments only showed a broad angle-velocity distribution with a maximum[3].Here, we report an investigation of the angle-velocity distribution as well as the vibrational stateone, based on the quasi-classical trajectory (QCT) method within the Gaussian binning (GB)procedure [4,5] for the pseudo-quantization of HOD vibrations (instead of the ordinary histogrambinning (HB) procedure that we employed in previous studies [1, 9]). The state-of- the-art WSLFHpotential energy surface (PES) was used in the calculations [6] (see also refs. [7,8]). Our predictionsare compared with experiment in Figs 1 and 2, which show that both sets of results are in closeagreement and differing from what occurred in previous QCT calculations [1,9]. Hence, thedifferences previously observed between QCT and experimental results come up mainly from aninadequate treatment of the pseudo-quantization of HOD vibrations, rather than from othergenuine quantum effects.Due to the difficulties of calculating a very large number of trajectories on the other state-ofthe-artPES available (YZCL2 surface) [10], this PES has not been considered here (calculations are~10 3 times more expensive than in the WSLFH surface). However, the similar QCT dynamicproperties found for the WSLFH and YZCL2 PESs [1,9] suggest that the YZCL2 surface should also leadto a satisfactory comparison between the QCT-GB and the experimental data [2]. From what weknow, the results shown here correspond to one of the best agreements between theory and highresolution experiments reported so far in the context of polyatomic reaction dynamics.Finally, although there is no experimental information available to compare with, additionalcalculations have been performed to explore the influence of vibrational excitation of D 2 (v=1,2) andOH (v=1-4) on the dynamics. The results evidence significant differences in the role played by the D-D and O-H bonds in the dynamics, as expected.This work has been supported by project CTQ2008-06805-C02-01 (Spanish Ministry of Science andInnovation). Thanks are also given to project SGR2009 17 (Autonomous Government of Catalonia).45

Figure 1: Angle-velocity distributions of the D atoms arising from the OH + D 2 reaction, in the center of mass velocity space:Experiment [2] (left); QCT-GB WSLFH (right). The vibrational states of HOD(v 1 ’,v 2 ’,v 3 ’) are given between parentheses (v 1 ’ isnot indicated, as it is always equal to zero).Figure 2: HOD(v 1 ’,v 2 ’,v 3 ’) vibrational populations from the OH + D 2 reaction: Experimental [2] (up); QCT GB WSLFH (down).Same comment on v 1 ’ as in Figure 1.References[1] J. D. Sierra, R. Martínez, J. Hernando, M. González, Phys. Chem. Chem. Phys. 11 (2009) 11520.[2] B. R. Strazisar, C. Lin, H. F. Davis, Science 290 (2000) 958.[3] M. Alagia, N. Balucani, P. Casavecchia, D. Stranges, G. G. Volpi, J. Chem. Phys. 98 (1993) 8341.[4] L. Bonnet, J.-C. Rayez, Chem. Phys. Lett. 277 (1997) 183.[5] J. Espinosa-Garcia, L. Bonnet, J. C. Corchado, Phys. Chem. Chem. Phys. 12 (2010) 3873. G. Wu, G. C. Schatz, G.Lendvay, D.-C. Fang, L. B. Harding, J. Chem. Phys. 113 (2000) 3150, Erratum J. Chem. Phys. 113 (2000) 7712.[6] D. Troya, M. J. Lakin, G. C. Schatz, M. González, J. Chem. Phys. 115 (2001) 1828.[7] M. J. Lakin, D. Troya, G. Lendvay, M. González, G. C. Schatz, J. Chem. Phys. 115 (2001) 5160.[8] J. D. Sierra, P. A. Enríquez, D. Troya, M. González, Chem. Phys. Lett. 399 (2004) 527.[9] M. Yang, D. H. Zhang, M. A. Collins, S.-Y. Lee, J. Chem. Phys. 115 (2001) 174.46

CONTRIBUTED TALK C7The dynamics of Cl + O 3 reaction: A theoretical study and comparisonwith experimental results.F. J. Aoiz 1 *, J. F. Castillo 1 , M. Menéndez 1 , and B. Martínez-Haya 21 Departamento de Química Física, Facultad de Química, Universidad Complutense, 28040Madrid, Spain.2 Departamento deSistemas Físicos, Químicos y Naturales. Universidad Pablo Olavide. 41013Sevilla, Spain.The Cl+O 3 reaction is of fundamental relevance in the scavenging of O 3 in the stratosphere[1,2]. As such, it has attracted a considerable interest, especially as far as its kineticsconcerns. Its dynamics, however, has received much less attention. The most detailed studyto date has been that carried out with crossed molecular beams measuring laboratoryangular distributions (LAB AD) and time-of-flight (TOF) spectra of the ClO product at severalcollision energies, whereby the scattering angle-recoil velocity distributions in the centre-ofmass(COM) were derived [3]. Although there have been previous ab initio calculations, theonly existing global potential energy surface (PES) was an empirical one based onprospective calculations of relatively low level. Electronic structure calculation for thissystem are particularly challenging for several reasons. The biradical character of the O3molecule poses serious problems because the Hartree–Fock (H-F) wave function is relativelypoor, and therefore some single reference post-H-F methods, such as MP2, may fail toreproduce the main features of the PES and its asymptotes. We present a global fulldimensional potential energy surface (PES) [5] which has been constructed by interpolationof quantum chemistry data using the GROW method developed by Collins and co-workers.Ab initio data points (energy, gradients and Hessian matrix elements) have been calculatedat the UQCISD/aug-cc-pVDZ level of theory. The ab initio calculations predict a markedlynon-coplanar (dihedral angle of 80 o ) transition state for the reaction, located very early inthe reactant valley and slightly below the energy of the reactants as long as the Cl spin–orbitsplitting is neglected. Extensive quasi-classical trajectory (QCT) calculations have beencarried out at several collision energies to investigate the reaction dynamics. The QCTexcitation function shows no threshold, displays a minimum at 2.5 kcal mol -1 collisionenergy, and then increases monotonically at larger collision energies. This behaviour isconsistent with a barrierless reaction dominated by an oxygen-abstraction mechanism. Thecalculated product vibrational distributions (strongly inverted for ClO) and rate constants arecompared with experimental determinations. Differential cross sections (DCS) summed overall final states are found to be in fairly good agreement with those derived from crossedmolecular beam experiments. Moreover, detailed simulations of the LAB AD and TOF spectrahave been carried out using the theoretical COM angle-velocity distributions rendering anexcellent agreement with the experimental raw data.[1] M. J. Molina and F. S. Rowland, Nature, 1974, 249, 810.[2] P. J. Crutzen and M. Oppenheimer, Clim. Change, 2008, 89, 143.[3] J. Zhang and Y. T. Lee, J. Phys. Chem. A, 1997, 101, 6485.[4] S. C. Farantos and J. N. Murrel, Int. J. Quantum Chem., 1978, 14, 659.[5] J. F. Castillo, F. J. Aoiz, and B. Martinez-Haya, Phys. Chem. Chem. Phys., 2011, 13, 8537.[6] M. J. T. Jordan, K. C. Thompson and M. A. Collins, J. Chem. Phys., 1995, 102, 5647. ibid. J. Chem.Phys., 1998, 108, 8302.* email: aoiz@quim.ucm.es47

CONTRIBUTED TALK C8Photophysics and photochemistry of calcium dimer on helium clusterM. Briant, A. Masson, M.A. Gaveau and J.M. MestdaghIRAMIS/SPAM, CEA-Saclay, FranceA convenient way to study physical or chemical process at an atomic scale which allows determiningits exact stoichiometry, is to use clusters as a medium. Two variants exist whether Van-der-Waalsclusters (argon, neon,...) or quantum clusters (helium nanodroplets) are used. This leads to theCluster Isolated Chemical Reaction (CICR) technique developed in our laboratory in the former case[1] and to the Helium Nanodroplet Isolation (HENDI) technique, developed in the group of Scoles [2].Both techniques are currently used in our laboratory. The guiding line of the present talk is thecalcium dimer Ca 2 which is formed on helium clusters by the sequential pick up of two Ca atoms. Itsphotodissociation and its reaction with N 2 O will be addressed.Helium clusters are grown by condensation in a supersonic beam (stagnation conditions: T 0 =10°K,P 0 =9 bar, D * =5 µm). The average size of the cluster is estimated to a few thousands [3]. Afterextraction by a skimmer, the helium clusters beam passes through a heated calcium vapour cell.Here, Ca atoms are picked-up by the helium clusters. They are believed to stay at the surface of theclusters [4]. When two of them are present on the same cluster, they migrate and associate togetheras the Ca 2 molecule since their association energy is higher [5] than the cluster temperature (0.4 K).Photodissociation studies: the clusters carrying the Ca 2 dimers are illuminated by a cw laserbetween 360 and 390 nm. This excites Ca 2 in a specific region of the potential energy curves, wherea non dissociative doubly excited configuration (correlating diabatically to Ca( 3 D)+Ca( 3 P)) is coupledto a singly excited configuration (correlating to Ca( 1 S)+Ca( 1 P)). An excited fragment is produced,Ca(6s6p 1 P). It is detected by recording the Ca(6s 2 1 S←6s6p 1 P) emission at 422.79 nm. Our formerworks will be reviewed during the talk [6,7], complemented by recent studies where a controllednumber of argon atoms are present in the helium nanodroplets in addition to Ca 2 . Competingdynamics where the Ca(6s6p 1 P) emitter is either free of bound to helium atoms or bound to argonatoms will be discussed.Reaction studies with N 2 O: a N 2 O effusive beam is crossed with the helium cluster beam, after theCa pick-up region. Hence clusters carrying Ca atoms and N 2 O molecules are generated. The N 2 Omolecules and Ca atoms which are present on the same cluster can migrate relative to each otherand react. No chemiluminscence signal is observed when a single Ca atom and a single N 2 O moleculeare present on the cluster, although such reaction was observed in the gas phase [8,9]. This might bedue to the existence of a yet unsuspected reaction barrier which cannot be overcome at the lowtemperature of the helium clusters. A chemiluminescent reaction is observed when two Ca atomsand at least one N 2 O molecule are present on the same cluster. A typical chemiluminescencespectrum is shown in figure 1. It is in close resemblance with a spectrum observed in argon matrixand assigned to the d 3 ,D 1 ' C a transitions of CaO [10]. The dynamics of thisreaction will be discussed.48

Figure 1: Chemiluminescence observed from helium clusters carrying 2 Ca atoms and at least oneN 2 O molecule.References[1] J.M. Mestdagh, M.A. Gaveau, C. Gée, O. Sublemontier and J.P. Visticot, Int. Rev. Phys. Chem. 16 (1997) 215.[2] F. Stienkemeier, J. Higgins, W. E. Ernst, and G. Scoles, Phys. Rev. Lett. 74 (1995) 3592.[3] F. Stienkemeier and K.K. Lehmann, J. Phys. B 39 (2006) R127.[4] F. Stienkemeier, F. Meier and H. O. Lutz, J. Chem. Phys. 107 (1997) 10816.[5] T. Bouissou, G. Durand, M.-C. Heitz, and F. Spiegelman , J. Chem. Phys. 113 (2010), 164317.[6] A. Masson, M. Briant, J.M. Mestdagh, M.A. Gaveau, Proceedings of the XXVIth International Symposium on rarefied GasDynamics, Ed 2011.[7] M.A. Gaveau, J.M. Mestdagh, T. Bouissou, G. Durand, M.C. Heitz, F. Spiegelman, Chem. Phys. Lett. 467 (2009), 260.[8] J.A. Irvin and P.J. Dagdigian, J. Chem. Phys. 74 (1981) 6178.[9] J.A. Irvin and P.J. Dagdigian, J. Chem. Phys. 73 (1980) 176.[10] C.S. Wei, S.W. Guo, and Y.P. Lee, J. Chem. Phys. 82 (1985) 2942.49

CONTRIBUTED TALK C9Time-resolved photoelectron spectroscopy of indole and5-hydroxyindoleRuth Livingstone 1 , Oliver Schalk 2 , Andrey E. Boguslavskiy 2 , Guorong Wu 2 , L. Therese Bergendahl 1 ,Albert Stolow 2 , Martin J. Paterson 1 and Dave Townsend 11 School of Engineering & Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UnitedKingdom2 Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, K1A0R6, CanadaTime-resolved pump-probe photoelectron spectroscopy was used to obtain information about thedynamics of electronic relaxation in gas-phase indole and 5-hydroxyindole following UV excitationwith femtosecond laser pulses centred at 249 nm and 273 nm. Our analysis of the data wassupported by ab initio calculations at the Coupled Cluster and CASSCF levels. The optically bright 1 L aand 1 L b electronic states of ππ* character and spectroscopically dark and dissociative 1 πσ* stateswere all found to play significant roles in the overall relaxation process. In both molecules weconclude that the initially excited 1 L a state decays non-adiabatically on a sub 100 fs timescale via twocompeting pathways, populating either the subsequently long-lived 1 L b state or the 1 πσ* statelocalised along the NH coordinate, which exhibits a lifetime on the order of 1 ps. This is evident inthe decay associated spectra that we may extract from our time-resolved data by globally fittingthree exponential functions (τ 1 , τ 2 and τ 3 ) and examining the fit amplitudes as a function of electronbinding energy, as illustrated in the figure below. In the case of 5-hydroxyindole, we conclude thatthe 1 πσ* state localised along the O-H coordinate plays little or no role in the relaxation dynamics atthe two excitation wavelengths studied.Figure: Decay associated spectra for indole following excitation at 249 nm50

CONTRIBUTED TALK C10Ionization of dimethyluracil dimers leads to facile proton transferin the absence of H-bondsAmir Golan a , Ksenia B. Bravaya b , Romas Kudirka c , Oleg Kostko a , Stephen R. LeoneAnna I. Krylov b , and Musahid Ahmed aa, d ,a Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720b Department of Chemistry, University of Southern California, Los Angeles, CA 90089-0482c The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley California 94720d Departments of Chemistry and Physics, University of California, Berkeley, CA 94720Efficient proton transfer (PT) through stacked pairs of methylated nucleic acid bases (NABs, 1,3-dimethyluracil) is observed upon ionization, in spite of the fact that methylation blocks the H-bonding sites and eliminates the H-bonded isomers. Proton transfer (PT) in dimers of Uracil (U) and1,3-dimethyluracil are investigated by tuneable vacuum-ultraviolet (VUV) synchrotron massspectrometry. Single photon ionization data is compared to numerical calculations of ionizationenergies and energetics for proton transfer in several possible dimer structures. While PT is knownto be very efficient in H-bonded NAB pairs, the measuered methylated species demonstrate a similareffect where about 85% of the ionized base pairs undergo PT. Experiments using deuterateddimethyluracil reveal that PT occurs from the methyl groups, and not from the aromatic CH sites.Numerical simulations show that contrary to H-bonded dimers, the PT reaction coordinate in the -stacked base pairs involves significant rearrangements of the two fragments, however, thecorresponding energy barrier to PT is surprisingly small (0.6 eV). This implies that methylation ofDNA does not prevent ionization-induced PT, which is important in radiation and oxidation inducedprocesses.51

CONTRIBUTED TALK C11Formulating models of non-equilibrium dynamicsin solution phase organic chemistryDavid R. GlowackiCentre for Computational Chemistry, University of Bristol, Bristol BS8 1TS, UKDavid.R.Glowacki@bristol.ac.ukMaster equation models are proving useful tools for quantitative modelling of chemical kinetics in arange of chemical systems relevant to gas phase combustion and atmospheric chemistry. The powerof the master equation approach lies in the fact that it provides a mechanism for tackling thecompetition between chemical reactions and weak collision relaxation processes. Previously, theapplication of master equation methodology to small molecule chemical dynamics has beenexclusively confined to gas phase systems; however, we have recently begun to extend thesemethods to condensed phase phenomena in conjunction with simple isolated binary collisionmodels. In particular, we have recently shown that product yields in alkene hydroboration, which is astaple reaction in synthetic organic chemistry, are determined by the competition between stepwisecollisional stabilization and unimolecular reaction of hot intermediates (J. Am. Chem. Soc., 2010, 132(39), 13621). Similarly, we have shown that a weak collision master equation provides a gooddescription of product yields obtained upon unimolecular reaction of bicyclopentadiene in solution,with a hot intermediate again playing an indispensable role (J. Am. Chem. Soc., 2011, 133 (14),5312). In both of these studies – and for solution phase non-equilibrium dynamics more generally –the issue of how to model energy transfer remains a key issue. Recent theoretical work in carryingout fully explicit atomistic simulations of non-equilibrium bimolecular dynamics (Science, 2011, 331(6023), 1423) has begun to provide detailed insight into solution phase energy transfer processesthat may be fed into master-equation sorts of approaches.52

CONTRIBUTED TALK C12Dynamic imaging of molecules using high harmonics generationV. Blanchet 1 , R. Cireasa 1 , E. Constant 2 , B. Fabre 2 , C. Handschin 2 , J. Higuet 2 , M. Yu. Ivanov 3 , Y.Mairesse 2 , E. Mével 2 , H. Ruf 2 , O. Smirnova 4 and N. Thiré 11 Laboratoire Collisions, Agrégats et Réactivité, IRSAMC, University of Toulouse,118 route de Narbonne, 31062 Toulouse Cedex 09, France2 Centre Lasers Intenses et Applications, University of Bordeaux,351, Cours de la Libération F-33405, Bordeaux, France3 Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2BW, United Kingdom4 Max-Born-Institute, 2a Max-Born-Strasse, Berlin D-12489, GermanyIn the last few years, high order harmonic generation (HHG) has emerged as a novel spectroscopictechnique for probing molecular structures and dynamics, including sub-femtosecond arrangementsof nuclei and electrons. This technique consists of measuring the spectrum of the coherent radiationemitted by molecules subjected to intense laser fields, as high-order harmonics of the driving fieldfrequency. The spectrum, phase and polarisation of the harmonics are sensitive to molecularinformation, as for example, the structures and symmetries of the highest occupied molecularorbitals (HOMO, HOMO-1,…). The yield of HHG is strongly dependent on the molecular alignmentand by controlling the angle between the molecular axes and the polarisation of the driving laserfield, the structure and symmetries these orbitals can be mapped out by the so-called tomographicimaging method.We illustrate the importance of the degree of molecular alignment in revealing molecularinformation from the HH spectra. Furthermore, we explore for the first time, the sensitivity of theHHG process to a more subtle orientational aspect of the generating medium: the handedness ofchiral molecules.To elucidate the processes involved in the HHG in small molecules, we used a 800 nm fs pump pulseto create nonadiabatic molecular alignment and a fs probe pulse (also 800 nm) to generate HH in thealigned samples. High-order harmonic spectra were recorded as a function of the alignment angle.By achieving a very high degree of alignment of the molecular axis we could reveal new features inthe HH spectra. The results obtained for CO 2 indicate that several ionization channels contribute tothe HHG, while for N 2 it seems that the new features are associated with the nonadiabatic dynamicsof the ion in the laser field.In order to investigate the potential of HHG for revealing chirality, we used gas-phase enantiopuresamples of fenchone (+ and -) and elliptically polarised driving laser field at 1850 nm. By measuringthe amplitude of the harmonic signal as a function of the driving laser ellipticity we could evidencethat the two enantiomers exhibit different response: the harmonic signal is not maximum for alinear laser polarization, but for a non-zero ellipticity whose sign depends on the consideredenantiomer. This indicates that the harmonic signal produced by an elliptical laser field isstereoisomer sensitive.53

CONTRIBUTED TALK C13Ion-molecule cold chemistry using molecular beams with a tunable velocity.M. T. Bell, J. M. Oldham, L. Harper and T. P. SoftleyDepartment of Chemistry, University of Oxford,Chemistry Research Laboratory, Oxford, OX1 3TA, U. K.This talk will describe an experimental method for studying ion-molecule reactive collisions at verylow energies. Building on our previous work using an electrostatic quadrupole guide as a source ofcold neutral molecules, we discuss a proof of principle study of the charge-exchange reactionbetween cold xenon ions and Stark decelerated ammonia molecules.Ammonia molecules from a pulsed supersonic expansion are produced at low velocities using theStark deceleration technique of Meijer and co-workers. The decelerated molecules are focussedusing pulsed electrostatic hexapoles into the centre of a radiofrequency ion trap where they collidewith cold xenon ions. A fast-opening mechanical shutter installed in the beamline is used to preventtransmission of the undecelerated molecules and carrier gas into the ion trap chamber.To prepare the target ions, the ion trap is loaded with calcium ions, which are then Doppler lasercooled to form a low-temperature ordered “Coulomb crystal” phase. Xenon ions are introduced byresonant multiphoton ionisation and then sympathetically cooled through their Coulomb interactionwith the laser-cooled ions. Reactive collisions of the Xe + ions with ND 3 molecules can be observed byimaging the spatial distribution of fluorescence produced by the laser-cooled calcium ions within themulticomponent Coulomb crystal. By varying the high voltage switching sequence applied to thedecelerator, the velocity of the ammonia molecules can be tuned from around 250 m/s to 35 m/s.For collisions with trapped xenon ions, this corresponds to collision energies (expressed intemperature units) from 65 K down to close to 1 K.54

Posters55

POSTER SESSION 1 P1-1Analysis of the HOOO torsional potentialJoseph M. Beames and Marsha I. LesterDepartment of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323Craig MurraySchool of Chemistry, University of Bristol, Bristol, UK BS8 1TSMychel E. Varner, and John F. StantonInstitute for Theoretical Chemistry, Department of Chemistry and Biochemistry, The University ofTexas at Austin, Austin, Texas 78712The hydrotrioxy (HOOO) radical has been identified previously as a potentially importantatmospheric species. Its atmospheric abundance is governed by the stability of HOOO with respectto dissociation in the central O-O coordinate. This is complicated by the presence of both cis andtrans-HOOO conformers separated by a barrier to isomerisation. In this work, 1 torsional levels of cisandtrans-HOOO and DOOO, observed previously via infrared action spectroscopy, 2 have been usedin conjunction with ab initio theory to obtain a torsional potential energy surface for HOOO. Highlevel electronic structure calculations based on the equation-of-motion coupled-cluster method forionized states (EOMIP-CCSD) are utilized to produce a torsional potential. Eigenvalues of thepotential are computed by diagonalizing the torsional Hamiltonian in a free-rotor basis. Uniformscaling of the theoretical potential by a factor of 1.35 yields vibrational frequencies in goodagreement with experiment, and allows prediction of the barrier height to isomerisation of ≈ 340cm -1 and relative stability of trans-HOOO with respect to cis-HOOO of ≈ 70 cm -1 . These results arecompared with other recent calculations of the cis to trans isomerisation path. Examination of theoptimized nuclear coordinates with respect to torsional angle suggests that the central O-O bondlength is strongly coupled to the torsion and is important in determining the relative stabilities of thetwo conformers. The scaled potential is then used to determine the torsional contribution to thepartition function for atmospheric modelling of HOOO.1 J. M. Beames, M. I. Lester, C. Murray, M. E. Varner, and J. F. Stanton, “Analysis of the HOOO torsional potential”, J. Chem.Phys. 134, 044304 (2011).2 E. L. Derro, T. D. Sechler, C. Murray and M. I. Lester, J. Chem. Phys. 128, 244313 (2008)56

POSTER SESSION 1 P1-2Collisional depolarisation in CN(A 2 Π): Experiment and theoryS.J. McGurk, K. G. McKendrick and M.L. CostenSchool of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, Scotland, UKWe present recent experimental and theoretical work on the collisional depolarization of rotationalorientation and alignment in the CN A 2 Π + Ar system. Circular or linear polarized one-photonexcitation on the A 2 Π-X 2 Σ + (4, 0) band was used to generate oriented and/or aligned A 2 Π (v = 4, j, F 1 e)rotational and fine structure levels. The excited CN A 2 Π was monitored via stimulated emission onthe A 2 Π-X 2 Σ + (4, 2) band using cw-frequency modulated spectroscopy. 1 Two separate types ofmeasurement are reported. In the first, the initially prepared level, j, is monitored with either circularSignal / arb. units1.00.80.60.40.20.0potential energy surfaces. 2References0 500 1000 1500 2000 2500Delay / nsCo-rotatingCounter-rotatingOrientationFM signal for j = 6.5 F 1e as a function of delaytime at [Ar] = 116 mTorr in 2 experimentalgeometries. Orientation defined asC I I I I coconcoconor linear probe polarization, and the collisional evolution of thepopulation and initially prepared orientation or alignment isobserved. In the second, an orientation is generated in a singleinitial fine structure resolved level, (v = 4, j = 6.5, F 1 e), and arange of product levels, (j', F 1 e) and (j', F 2 f), populated byrotational energy transfer are monitored using circular probepolarization. This provides measurements of the state-to-statepopulation transfer rate constants, and significantly, the stateto-stateorientation multipole transfer efficiency,1E j,j.We discuss these experimental results in the context of recentcomplementary quantum scattering calculations on ab-initio[1] I. Ballingall, M. F. Rutherford, K. G. McKendrick, and M. L. Costen, Molecular Physics 108, 847 (2010).[2] M. H. Alexander and P. J. Dagdigian, Unpublished (2011).57

POSTER SESSION 1 P1-3Specific heat spectra of long-range correlated DNA moleculesP.W. Mauriz 1 and E.L. Albuquerque 21 Departamento de Física, IFET, 65.020-300 São Luís-MA, Brazil2 Departamento de Biofísica e Farmacologia, UFRN, 59072-9 70 Natal-RN, BrazilThe DNA molecule is often described as a one-dimensional random chain, being defined as asequence of four possible nucleotides which shapes the structure of the amino acids to formproteins. Its sequence can be considered as a symbolic arrangement of a four letter alphabet,namely guanine (G), adenine (A), cytosine (C) and thymine (T), and nothing prevents that the DNAchain can be grown following quasiperiodic sequences [1].One of the most studied models of a one-dimensional quasiperiodic structure is the Fibonaccilattice, which exhibits a critical behavior of localization of the eigenstates independent of the twovalues taken by the substitution potential. The criticality of the localization is revealed by a singularcontinuous energy spectrum consisting of a Cantor set of zero Lebesgue measure for the FibonacciHamiltonian. Another one, is the Rud in-Shapiro sequence, which holds a unique position inasmuchas its correlation measure is absolutely continuous, such as for random sequences. Based on thisfeature one would expect the RudinShapiro lattice to have properties close to that of a randomsystem, especially since its correlation measure has a uniform density.It is the aim of the present work to contribute to this subject considering the energy spectra of along-range correlated quasiperiodic ladder sequences (Fibonacci and Rudin-Shapiro type),mimicking a DNA molecule. Our model Hamiltonian is the effective tight -binding model describingone electron moving in a chain with a single orbital per site and nearest-neighbor interactions [2].Taking them as the energy spectrum of a single fermionic particle, we will compute the specific heatof a system of non-interacting fermions and discuss its features in connection with the scaleinvariance character of their underlying multi-fractal energy spectrum. Comparisons are then madewith a real DNA sequence, namely the human chromosome 22 (Ch22).AcknowledgmentsThis work received financial support from the Brazilian Research Agencies CAPES (PROCAD and RedeNanoBioTec), CNPq (INCT-Nano(Bio)Simes) and FAPERN/CNPq (Pronex).References[1] E.L. Albuquerque and M.G. Cottam, Phys. Rep. 376, 225 (2003).[2] D.A. Moreira, E.L. Albuquerque and D.H.A.L. Anselmo, Phys. Lett. A 372, 5233 (2008).58

POSTER SESSION 1 P1-4Coulomb explosion of rare gas dimers in collisions with slowhighly charged ions: stereodynamical effectsT. Ohyama-Yamaguchi (1) , A. Ichimura (2)(1) Tokyo Metropolitan College of Industrial Technology, Tokyo 140-0011, Japan(2) Institute of Space and Astronautical Science, JAXA, Sagamihara 252-5210, JapanMuch attention has been called to Coulomb explosion of molecules in collisions with slow (velocitiesof 0.01 < v < 1 au) highly charged ions on a basis of momentum imaging technique. Such an experimentpermits us to measure dissociating ion pair (Q, Q ′ ) distribution for a ‘fixed-in-space’ molecule,revealing many-electron stereo-dynamics in collision processes. In contrast with covalent molecules,however, little effort has been devoted to rare gas dimers. In a previous paper [1], we investigatedmultiple ionization of rare gas (Ne) dimers by developing a three-center Coulombic over-barriermodel. It was predicted that ion pairs were populated exclusively with Q = Q ′ and Q = Q ′ ± 1,indicating a remarkable orientation-dependent even-odd behavior in the distribution over thenumber r = Q + Q ′ of removal electrons.However, this result seems counter-intuitive; highly charge-asymmetric ion pairs (|Q− Q ′ | ~ 2) shouldbe considerably populated owing to a long internuclear distance in the rare gas dimer. In the presentwork, we address this problem, stimulated by a recent experiment [2] done at GANIL. We modify thethree-center over-barrier model by introducing a screening parameter s between two atomic sites inthe dimer [3]. At a critical distance of electron removal from the active site, an electron alreadyremoved from the non-active site still partially screens its original ion core when seen from a distantactive site. The screening effect is found crucial for populating ion pairs with charge difference morethan one (see the figure).Figure: Ion-pair formation cross sections calculatedwith the present model taking thescreening parameter as s = 0 (no screening), s = 1(complete screening) and s = 0.4 (partialscreening). The cross sections are compared withthe experimental results [2], normalized with thepresent calculation at s = 0.4 for(Q,Q ′ ) = (2,1).References1. T. Ohyama-Yamaguchi and A. Ichimura, Nucl. Instr. and Meth. B 205, 620 (2003).2. J. Matsumoto et al., Phys. Rev. Lett. 105, 263202 (2010).3. T. Ohyama-Yamaguchi and A. Ichimura, to be published in Phyica Scripta T.59

POSTER SESSION 1 P1-5QCT study of the CD + D 2 reaction kineticsErnesto García 1 and Miguel González 21 Departamento de Química Física, Universidad del País Vasco, Vitoria, Spain2 Departament de Química Física i IQTC, Universitat de Barcelona, Barcelona, SpainThe CH + H 2 reaction is relevant in combustion chemistry and astrochemistry and its kinetics hasbeen studied experimentally over a wide T interval [1-3], including also the isotopic variants CH + D 2[1,2] and CD + D 2 [1,4]. Besides, the D atom exchange reaction, CH + D 2 → CD + HD, has been studiedusing crossed molecular beams [5]. From a theoretical perspective, this reaction can probably beconsidered a benchmark system for tetra-atomic reactions with a deep well (of -4.828 eV withrespect to the reactants asymptote) in the minimum energy reaction path associated to the CH 3radical. Theoretical studies (dynamics and kinetics) have been previously reported on CH + H 2 → CH 2+ H employing a centrifugal sudden (CS) time-dependent quantum method [6,7]. The reduceddimensionality of these studies can be overcame by means of the quasiclassical trajectory (QCT)method. Nevertheless, due to its classical nature, this method can lead to the breakdown of the zeropoint energy (ZPE) of products, and in this system this is particularly important for CH + H 2 → CH 2 + H(abstraction) due to its endothermicity (0.145 eV).The ZPE problem has been addressed by us recently in QCT calculations on the kinetics of the CH +H 2 [8] and CH(v=0,1) + D 2 , H 2 reactions [9], where the capture process leading to CH 3 and all reactionchannels were investigated. Thus, a pragmatic approach, in which only trajectories (reactive or notreactive) leading to molecular species with vibrational energy above the corresponding ZPE value aretaking into account, has been applied. Satisfactory results have been obtained for most of theprocesses for which there is experimental information available: CH + H 2 → CH 2 + H (abstraction) [8]and CH(v=1) + D 2 , H 2 global reactions [9]. However, a poor agreement with experiments has beenobtained for the rate coefficient of the CH(v=0) + D 2 global reaction [9]. Even though the source ofthis problem has not been yet fully understood, it is quite clear that it arises from the theoreticaldescription of CH + D 2 → CD + HD (exchange) and CH + D 2 → CD 2 + H (abstraction-exchange).Here, we present a QCT study of the CD + D 2 reaction kinetics in a wide T interval (300-1200 K).Figure 1 shows the theoretical global rate coefficients (k all ) together with the experimentalinformation available. From the figure it comes out that a rather good agreement with experimentsonly occurs for T above 700 K and when the one-dimensional Gaussian-binning (1GB) approach [10]to treat the ZPE breakdown is used. However, when the pragmatic approach rather satisfactorilyused in refs. [8,9] (criteria C2 and C2e) is applied only the slope of the Arrhenius’ plot is describedreasonably well, while the resulting global rate coefficients are about one order of magnitude abovethe measured ones. Figure 2 shows the dependence of the CD + D 2 → CD 2 + D abstraction ratecoefficient (k a ) with temperature but, unfortunately, no experimental results are available tocompare with. The differences of k a with respect to k all substantially increase as T decreases, becausethe exchange process becomes progressively more important. Thus, while both rate coefficients aresimilar at the highest T explored, k a is about one order of magnitude smaller than k all at the lowest Texamined.60

This work has been supported by the projects CTQ2008-02578 and CTQ2008-06805-C02-01 (SpanishMinistry of Science and Innovation). Thanks are also given to the project SGR2009 17 (AutonomousGovernment of Catalonia).Figure 1: QCT and experimental [1, 4] CD + D 2 global rate coefficients. The results labelled as QCT are the onesdirectly obtained from the QCT method, while the results obtained from different ZPE treatments are labelledas C2, C2e [8,9] and 1GB [10].ReferencesFigure 2: QCT CD + D 2 → CD 2 + D abstraction rate coefficients. Same comment as in Fig 1.[1] C. T. Stanton, N. L. Garland, H. H. Nelson, J. Phys. Chem. 95 (1991) 1277.[2] R. A. Brownsword, A. Canosa, B. R. Rowe, I. R. Sims, I. W. M. Smith, D. W. A. Stewart, A. C. Symonds, D. Travers, J. Chem.Phys. 106 (1997) 7662.[3] D. Fulle, H. Hippler, J. Chem. Phys. 106 (1997) 8691.[4] M. R. Berman, M. C. Lin, J. Chem. Phys. 81 (1984) 5743.[5] R. G. Macdonald, K. Liu, J. Chem. Phys. 93 (1990) 2443.[6] J. Mayneris, A. Saracibar, E. M. Goldfield, M. González, E. Garcia, S. K. Gray, J. Phys. Chem. A 110 (2006) 5542.[7] A. Saracibar, E. M. Goldfield, S. K. Gray, J. Phys. Chem. A 112 (2008) 12588.[8] M. González, A. Saracibar, E. Garcia, Phys. Chem. Chem. Phys. 13 (2011) 3421.[9] M. González, J. Mayneris-Perxachs, A. Saracibar, E. Garcia, Phys. Chem. Chem. Phys. (accepted).[10 G. Czakó, J. M. Bowman, J. Chem. Phys. 131 (2009) 244302.61

POSTER SESSION 1 P1-6Time-dependent quantum dynamics study of the Ne + H 2 + (v 0 =0-4, j 0 =1) →NeH + + H and O + H 2 + (v 0 =0, j 0 =0) → OH + + H, OH + H + reactionsPablo Gamallo, 1 Miguel Paniagua, 2 Rodrigo Martínez 3 and Miguel González 11 Departament de Química Física i IQTC, Universitat de Barcelona, Spain2 Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, Spain3 Departamento de Química, Universidad de La Rioja, SpainIon-molecule and related reactions can play a relevant role in numerous interesting situations, e.g.,electric discharges, planetary ionospheres and interstellar processes. Although they can be studiedin molecular beam experiments in a wide range of collision energies (E col ), they are often difficultsystems to investigate theoretically, because electronically non-adiabatic processes involving severalpotential energy surfaces (PESs) can rather easily occur [1].In the first part of this work, we have studied the dynamics of the moderately endoergic protontransfer elementary reaction in the gas phase Ne + H + 2 (v 0 =0-4, j 0 =1) → NeH + + H, D º o = 12.5 kcalmol -1 (reaction (1)) using a quantum dynamics treatment and analyzing the effect of vibrationalexcitation of H + 2 and collision energy on reactivity. This is probably the reaction for which moredetailed measurements on the influence of vibrational excitation on reactivity are available [2,3].Reactants and products adiabatically correlate on the ground 1 2 A’ PES of the NeH + 2 system, whichhas a collinear [Ne-H-H] + minimum placed along the minimum energy path (MEP). Reaction (1)differs from the more complex Ar, Kr + H + 2 reactions, where several PESs are involved, which makesthe Ne + H +2 system very attractive for high level theoretical studies (see, e.g., the quantumdynamics studies of refs. [4-6]).Coupled channel reaction dynamics calculations has been carried out for reaction (1), via the timedependentreal wave-packet [7] and flux [8] formalisms (CC-RWP method), and using the LZHHanalytical potential energy surface [6]. The reaction probabilities have been obtained for severaltotal angular momentum quantum number (J) values selected, taking into account the Corioliscouplings. Furthermore, in order to determine the reaction cross section for each vibrational level ofH + 2 , as a function of collision energy, the other relevant partial-wave reaction probabilities wereapproximated via a J-shifting based interpolation technique satisfactorily employed in recent works[9-12]. The cross sections ( ) obtained for reaction (1) (Fig 1) are in good agreement with thev0 , j 0 1PFI-PESICO experimental data [2], particularly at the lower collision energies (Table 1). Moreover,relative cross sections have been calculated as well, obtaining a good agreement with TESICOmeasurements [3] and with centrifugal sudden RWP quantum dynamics calculations [4] (CS-RWPmethod). Hence, the strategy used in the present study is especially useful when a significantnumber of reaction conditions have to be explored.Similar calculations have been performed on the O + H 2 + reaction (reaction (2)), which is probably ofinterest in astrochemistry. Rather surprisingly, only an investigation has been reported so far on thissystem (ab initio MRCI-SD(T) aug-cc-pVQZ based analytical PESs, and QCT and quantum dynamics(CS-RWP) calculations) [13]. This system has two possible reaction channels. The first channel leadsto the OH + + H products through a H + transfer occurring on the ground PES, 2 A’’ (exoergicity ≈ 2.7eV), which correlates with H 2 O + (X). The second channel leads to OH + H + via a H atom transfer on thefirst excited PES, 2 A’ (exoergicity ≈ 1.6 eV), which correlates with H 2 O + (A). The dynamic properties ofboth reaction channels are similar and rather easy to interpret (both PESs are barrierless and have a62

deep minimum in the MEP). The larger reactivity of the ground PES (H + transfer) can be attributed toits more attractive character and the presence of the deepest minimum (H 2 O + (X)) on it. Ratecoefficients for H + transfer are about three times the rate coefficients for H atom transfer. Moredetails on reaction (2) will be given in the COMET 2011 meeting. It is expected that this work willencourage experimentalists to carry out investigations on this interesting reactive system. This workhas been supported by the Spanish Ministry of Science and Innovation (Project No. CTQ2008-06805-C02-01). Thanks are also given to the Autonomous Government of Catalonia (Grant No. SGR200917).Figure 1: Cross section as a function of collision energy and vibrational state of H 2 + .Table 1: Cross sections (Å 2 ) at selected collision energies and vibrational statesE col =0.7 eVE col =1.7 eVv 0 Exp. [2] CS-RWP [4] CC-RWP Exp. [2] CS-RWP [4] CC-RWP0 0.260.08 0.11 0.26 0.380.11 0.23 0.391 2.20.7 1.22 3.33 1.600.06 1.09 1.732 5.241.57 3.01 6.03 3.060.13 3.17 4.023 7.292.19 5.02 8.54 4.140.15 4.58 6.214 9.552.89 6.42 10.17 5.320.13 5.79 7.61References[1] R. A. Dressler, Y. Chiu, D. J. Levandier, X. N. Tang, Y. Hou, C. Chang, C. Houchins, H. Xu, C. Y. Ng, J. Chem. Phys. 125(2006) 132306.[2] T. Zhang, X.-M. Qian, X. N. Tang, C. Y. Ng, Y. Chiu, D. J. Levandier, J. S. Miller, R. A. Dressler, J. Chem. Phys. 119 (2003)10175.[3] Z. Herman, I. Koyano, J. Chem. Soc., Faraday Trans. 2 83 (1987) 127.[4] J. Mayneris, J. D. Sierra, M. González, J. Chem. Phys. 128 (2008) 194307.[5] J. Mayneris-Perxachs, M. González, J. Phys. Chem. A 113 (2009) 4105.[6] S.-J. Lv, P-Y. Zhang, K.-L. Han, G.-Z. He, J. Chem. Phys. 132 (2010) 014303.[7] S. K. Gray, G. G. Balint-Kurti, J. Chem. Phys. 108 (1998) 950.[8] A. J. H. Meijer, E. M. Goldfield, S. K. Gray, G. G. Balint-Kurti, Chem. Phys. Lett. 293 (1998) 270.[9] S. Akpinar, P. Defazio, P. Gamallo, C. Petrongolo, J. Chem. Phys. 129 (2008) 174307.[10] P. Gamallo, P. Defazio, M. González, C. Petrongolo, J. Chem. Phys. 129 (2008) 244307.[11] P. Gamallo, P. Defazio, J. Chem. Phys. 131 (2009) 044320.[12] P. Defazio, P. Gamallo, M. González, C. Petrongolo, J. Phys. Chem. A 114 (2010) 9749.[13] M. Paniagua, A. Aguado, R. Martínez, J. Mayneris-Perxachs, M. González (submitted)63

POSTER SESSION 1 P1-7Algebraic approach to collinear reactive collisionsusing quasi-classical natural coordinatesTim Wendler and Manuel BerrondoBrigham Young University, USAWe calculate transition probabilities between discrete states of a diatomic molecule induced by anincoming atom. Our prototype Hamiltonian is constructed treating the translation classically and theinternal variables quantum mechanically. The corresponding equations of motion are coupled quasiclassically.We present applications to a canonical ensemble of initial conditions as well as results forthe time dependence of transition probabilities for different initial and final states. In the reactivecase we are driven to using natural coordinates i.e. the reaction coordinate and the transversevibrational coordinate.64

POSTER SESSION 1 P1-8Theoretical studies of boron-containing compounds in aqueous solution §Georgia M.A. Junqueira *a , Letícia C. Rocha a , Vitor T. Cotta b , Eloi T. César aa Departamento de Ciências Naturais, Colégio de Aplicação Jo˜ao XXIII,Universidade Federal de Juiz de Fora, 36015-260 Juiz de Fora, MG, Brasilb Escola Estadual Fernando Lobo, 36025-001 Juiz de Fora, MG, Brasil* e-mail:georgia.junqueira@ufjf.edu.brBoron-containing compounds are of increasing interest in the medical chemistry field [1, 2]. It wasrecently shown that a class of boron-containing compounds can inhibit the HIV protease, a key enzymeinvolved in replicating the virus that causes Aids [1]. Boronic acids RB(OH)2 (See Figure 1) areparticularly suited for drugs design owing to their low toxicity and stability under physiologicalconditions [2].Figure 1: The optimized geometry of boric acid B(OH)3 at MP2/aug-cc-pVDZ level of theory.Among all possible solvents, water is the natural biological solvent it is involved in all processesrelated to life. Thus, the purpose of the present study is to gain some insight about solvent and substituenteffects on the molecular properties of RB(OH)2 with R = OH, CH3, C 6 H 5, NH2 and NO2 inaqueous solution. For this, Monte Carlo simulations were performed using standard procedures forthe Metropolis sampling technique and periodic boundary conditions in a cubic box. In allsimulations one solute molecule RB(OH)2 plus 500 water molecules were used (See Figure 2).Figure 2: One boric acid molecule and the first solvation shell with 18 water molecules.Specifically, structural and thermodynamic properties of a series of boron-containing compounds arebeing obtained at condensed phase and will be reported. Furthermore, a discussion on the roleplayed by hydrogen bonding between boronic acids and water will be presented. Gas phasecalculations were performed by means of GAMESS package [3] and Monte Carlo simulations weredone using DICE program [4].§ This work is being developed by high school students supported by the PROBIC-Jr ProgramaInstitucional de Bolsas de Iniciação Científica Jánior FAPEMIG/UFJF.References[1] P. Rezácová etal., J. Med. Chem. 52 (2009) 7132.[2] A. Tafi etal., J. Med. Chem. 40 (2005).[3] Gamess Version, 22 Feb 2006 (R5), Iowa State University, M. W. Schmidt et al., J. Comput. Chem. 14 (1993) 1347.[4] K. Coutinho, S. Canuto, DICE: A Monte Carlo Program for Molecular Liquid Simulation, University of São Paulo,Brazil, 1997.65

POSTER SESSION 1 P1-9Femtosecond photodissociation dynamics in ClN 3D. Staedter 1 , N. Thire 1 , P. Samartzis ,2 and V. Blanchet 11 Universite de Toulouse, UPS, 118 route de Narbonne, F-31062 Toulouse, France2 The Institute of Electronic Structure and Laser, Foundation of Research and Technology, Hellas,Iraklion 71110, GreeceAzide (X-N 3 ) UV photochemistry (where X can stand for H, I, Cl, Br, F) proceeds through twopathways producing NX + N 2 and X + N 3 where N 3 can appear not only in a linear geometry but alsoas cyclic-N3, a unique all-nitrogen ring [1]. Cyclic-N 3 is stabilized by high (~1 eV) barriers todissociation or isomerization to its linear form. Previous work in the ns regime [2-5] determinedthe Cl-N3 bond energy to 1.86 eV and found evidence for cyclic-N 3 production below 250 nm, withits yield increasing as wavelength is decreased.Here we report the first time-resolved study of photochemistry of ClN 3 by femtosecond velocitymap imaging (fs-VMI). Goal of the experiment is to elucidate the ultrafast dynamics that lead to acyclic-N 3 production. The photodissociation of ClN 3 is studied at two different energies, namelyaround 4.6 eV (268 nm) where only linear N 3 is produced and around 6.2 eV (200 nm) wheremainly cyclic-N3 is produced. In order to detect this elusive N 3 cyclic radical, we utilize the smalldifference in ionization potential (~0.47 eV) between the cyclic and linear geometry. Besidesdissociation, time- resolved photofragment images also provide information on ClN 3 dissociativeionization dynamics.Figure: a) pump (268 nm) - probe (800nm) signal of N 3 as function of the time delay. b)N 3 images in a linear configuration at -1500 fs and +1500 fs delay.References[1] P. C. Samartzis and A. M. Wodtke, Phys. Chem. Chem. Phys., 2007, 9, 3054-3066.[2] A. E. Douglas and W. J. Jones, Can. J. Phys., 1965, 43, 2216.[3] A. Quinto-Hernandez, Int. J. M. Spectrom. 265 (2007) 261–266[4] N. Hansen and A. M. Wodtke, J. Phys. Chem. A, 2003, 107, 10608–10614.[5] M. Bittererova, H. Ostmark and T. Brinck, J. Chem. Phys., 2002, 116, 9740–9748.[6] N. Hansen, A. M. Wodtke, A. V. Komissarov and M. C. Heaven, Chem. Phys. Lett., 2003, 368, 568–573.66

POSTER SESSION 1 P1-10Electronic conductance in arrays of DNA finite segmentsE.L. AlbuquerqueDepartamento de Biofísica e Farmacologia, UFRN, 59072-9 70 Natal-RN, BrazilThe field of nanotechnology has emerged as one of the most important areas of research in thenear future. While scientists have been long aspiring to controllably and specifically manipulatestructures at the micrometer and nanometer scale, nature has been performing these tasks andassembling structures with great accuracy and high efficiency using specific biological moleculessuch as DNA and proteins. Numerous algorithms have been introduced to characterize andgraphically represent the genetic information stored in the DNA nucleotide sequence. The goal ofthese methods is to generate representative pattern for certain groups of sequences. Although theconstruction of nanometer-scale circuits remains problematic, the use of molecular recognitionprocesses and the self-assembly of molecules into supramolecular structures might help overcomethese difficulties. In this context, the ability to choose the sequence of nucleotides, and henceprovide the addressability during the self-assembly processes, besides its inherent molecularrecognition, makes DNA an ideal molecule for these applications [1].With this aim in mind, we report here a numerical study of electronic conduction in π-stackedarrays of DNA double-strand finite segments, made up from the nucleotides guanine, adenine,cytosine, and thymine, forming a Rudin-Shapiro (RS) quasiperiodic sequence, whose structurepresents long-range pair-correlation. It is constructed starting from a guanine nucleotide as seedand following its inflation rule. For comparison, we show also the electrical transport properties fora genomic DNA sequence considering a segment of the first sequenced human chromosome 22(Ch22). We obtained that the long-range correlations present in Ch22 and RS sequences areresponsible for the slow vanishing of some transmission peaks as the segment size is increased,which may promote an effective electronic transport at specific resonant energies of finite DNAsegments. On the other hand, much of the anomalous spread of an initially localized electron wavepacket can be accounted by short-range pair correlations on DNA. This finding suggests that asystematic approach based on the inclusion of further short-range correlations on the nucleotidedistribution can provide an adequate description of the electronic properties of DNA segments. Ourtheoretical method uses Dyson's equation together with a transfer-matrix treatment, within anelectronic tight-binding model Hamiltonian describing one electron moving in a chain, suitable todescribe the DNA segments [2]. The electronic density of states is calculated stressing the regions offrequency where the transfer function is complex.AcknowledgmentsThis work received financial support from the Brazilian Research Agencies CAPES (PROCAD andRede NanoBioTec), CNPq (INCT-Nano(Bio)Simes) and FAPERN/CNPq (Pronex).References[1] P. Carpena et al., Nature 418, 955 (2002).[2] R.G. Sarmento, E.L. Albuquerque et al, Phys. Lett. A 373, 1486 (2009)67

POSTER SESSION 1 P1-11Electronic transport in DNA segments with diluted baseU.L. FulcoDepartamento de Biofísica e Farmacologia, UFRN, 59072-9 70 Natal-RN, BrazilThere has been a tremendous interest in recent years in developing concepts and approaches forself- assembled systems, searching for their electronic and optical applications. The ability tochoose the sequence of nucleotides and hence provide addressability during the self-assemblyprocesses, makes DNA an ideal molecule for these applications [1]. The DNA does not primarilypresent an electron/hole-transfer problem, and its suitability as a potential building block formolecular devices may not depend only on the long-distance transfer of electrons and holesthrough the molecule. The reason for that lies in the mechanism itself: it fails to explain thepersistence of efficient charge transfer when the transfer rates do not decrease rapidly with thetransfer distance. Fortunately, its π-stacked array of base pairs does indeed provide an appropriatepathway for long-range charge transport, although the mechanisms for long-range transport andshort -range transfer may differ entirely. Strong stacking interactions result in the fastest electrontransferkinetics, whereas dynamical motion of the base pairs and reactant energetics alsomodulate the distance dependence of DNA-mediated charge transport, reducing its efficiency.In this work, we present a model for describing electrical conductivity along poly(CG) and poly(CT)DNA segments with diluted base pairing within a tight-binding Hamiltonian approach. The basepairing is restricted to occurring at a fraction p of the cytosine (C) nucleotides at which a guanine(G) nucleotide is attached. We show that the Schrodinger equation can be mapped exactly ontothat of the one -dimensional Anderson model with diluted disorder [2]. Using a Green functionformalism as well as exact diagonalization of the full one-dimensional Hamiltonian of finitesegments, we compute the density of states, the wavefunction of all energy eigenstates and theircorresponding localization lengths. We show that the effective disorder introduced by the dilutedbase pairing is much stronger in poly(CG) than in poly(CT) segme nts, with significant consequencesfor the electronic transport properties. The electronic wavepacket remains localized in the poly(CT)case, while it acquires a diffusive spread for the poly(CG)-based sequence.AcknowledgmentsThis work received financial support from the Brazilian Research Agencies CAPES (PROCAD andRede NanoBioTec), CNPq (INCT-Nano(Bio)Simes) and FAPERN/CNPq (Pronex).References[1] E.L. Albuquerque, M.S. Vasconcelos, M.L. Lyra and F.A.B.F. de Moura, Phys. Rev. E 71, 021910 (2005).[2] F.A.B.F. de Moura, M.L. Lyra and E.L. Albuquerque, J. Phys.: Cond. Matter 20, 075109 (2008).68

POSTER SESSION 1 P1-12Current–voltage characteristics of a DNA-like double-strand moleculeL.R. da Silva 1 and U.L. Fulco 21 Departamento de Física, UFRN, 59072-9 70 Natal-RN, Brazil2 Departamento de Biofísica e Farmacologia, UFRN, 59072-9 70 Natal-RN, BrazilDue to their potential applications in nanoelectronics, there has been a growing interest in thesynthesis, characterization, and the electronic properties of DNA-based molecules with periodicnucleotide sequences [1]. Using a full range of physical and biochemical methods, studies havenow established that double helical DNA is a medium for the efficient transport of electrons,triggering a series of experimental and theoretical investigations [2]. The earliest studies involvedphysical measurements of current flow in DNA fibers, and led to a mixture of conclusions, somesuggesting high electron mobility through DNA, others indicating no conductivity. In fact, oneexperiment even pointed to DNA as a superconductor. These physical studies have not yet beenreconciled with one another. The variations probably depend heavily upon the connectionsbetween the DNA and the electrodes used, as well as upon the integrity of the DNA itself in theabsence of water and exposed to very high voltages. Besides, these experiments have underscorednot only that the DNA base pair stack can mediate hole and electron transport chemistry, but alsothe exquisite sensitivity of the charge transport through the DNA structure.In view of that, we study the one-electron states in double-strand binary DNA segments. Ourtheoretical model is based on a tight-binding Hamiltonian [3], together with a transfer matrixtechnique employed to simplify the algebra which can be otherwise quite involved. We consider amodel in which the DNA molecule is sandwiched by two electrodes (donnor-DN and acceptor-AC,respectively), following a Fibonacci (FB) and a Rudin–Shapiro (RS) quasiperiodic structures, andcompare them to the DNA sequence of the first sequenced human chromosome 22 (Ch22). Weinvestigate the conductivity of the DNA molecule models through their electron transmittancecoefficient. Furthermore, by solving numerically a time-independent Schršdinger equation, wecompute also some basic properties of the I–V characteristics, for all DNA models considered here.AcknowledgmentsThis work received financial support from the Brazilian Research Agencies CAPES (PROCAD andRede NanoBioTec) and FAPERN/CNPq (Pronex).Reference[1] K.H. Yoo, etal., Phys. Rev. Lett. 87(2001)198102.[2] S. Delaney, J.K. Barton, J. Org. Chem. 68 (2004) 6475.[3] L.M. Bezerril, D.A. Moreira, E.L. Albuquerque, U.L. Fulco, et al, Phys. Lett. A 373, (2009) 3381.69

POSTER SESSION 1 P1-13Stepwise photocatalytic dissociation of CD 3 OH on TiO 2 (110)Qing Guo 1) , Chenbiao Xu 1), +) , Zefeng Ren 1),*) , Wenshao Yang 1) , Zhibo Ma 1) , Dongxu Dai 1) , Tim Minton 2),#) , Hongjun Fan 1), *) 1), *), Xueming Yang1)State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics,457 Zhongshan Road, Dalian 116023, Liaoning, P. R. China2) Also with School of Physics and Optoelectric Engineering, Dalian University of Technology,Dalian, Liaoning 116023, CHINA3) CAS Visiting Senior Scientist from Department of Chemistry, Montana State University, Bozeman,MT 59717, USATiO 2 is one of the most important metal oxide due to its participation in enormous technologicalprocesses.[1-3] Photodegradation of organic molecules and water splitting have received enormousattention, which have tremendous potential applications in both environmental cleanup and clearenergy. It has been reported that adding methanol into water could dramatically enhance thephotocatalytic activity of TiO 2 for water splitting to produce hydrogen.[5] Therefore it could give keyinsights into the photocatalytic dynamics on TiO 2 by learning the methanol photocatalytic chemistryon TiO 2 at the atomic and molecular level.Photocatalytic dissociation of CD 3 OH on TiO 2 (110) has been studied by the photocatalysis -TPDapparatus developed in our laboratory recently. Nascent products, such as formaldehyde on the Ti 5csites and H- and D-atoms on bridge-bonded oxygen (BBO) sites, have been detected through TPDmeasurements after different laser irradiation time. Experimental results show that the transfer ofhydroxyl H-atom and methyl D-atom in CD 3 OH to the BBO sites is a stepwise process in which the H-atom transfer proceeds first and then followed by the methyl D-atom. Theoretical calculationsindicate that the first step hydroxyl hydrogen dissociation has a small energetic barrier while thesecond step of D-atom dissociation from CD 3 O-Ti 5c has a much larger barrier, in good agreementwith the experimental results.References[1] A. Fujishima and K. Honda, Nature, 1972, 238, 37.[2] H. Idriss, M.A. Barteau, Adv. Catal. 45 (2000) 261.[3] B. O’Regan, M. Gr€atzel, Nature 353 (1991) 737.[4] Tracy L.Thompson and John T. Yates, Jr, Chemical Reviews, 2006, Vol. 106, No. 10[5] T. Kawai, T. Sakata, J. C. S. Chem. Comm. 24, 694 (1980).70

POSTER SESSION 1 P1-14Reactivity inhibitation by antisymmetric stretching excitation inthe dual-mechanism reaction O( 1 D) + CH 4Huilin Pan, Quan Shuai, Jiayue Yang, Dong Zhang, Bo Jiang, Dongxu Dai, Xueming YangState Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, ChineseAcademy of Sciences, Dalian, Liaoning 116023, P. R. ChinaDifferent forms of energy play distinct roles in chemical reactions 1 . How does the additionalvibrational energy of the reactant work along the reaction coordinate? This problem is extremelyimportant in understanding details of reaction dynamics. Accordingly, we performed a series of crossbeamexperiments of the dual-mechanism reaction O( 1 D) + CH 4 (ν 3 =0, 1) → OH + CH 3 , on a newlybuilttime-sliced ion velocity imaging machine 2 at collision energies ranging from 3.23 to 6.70kcal/mol. One of the reaction products CH 3 was state-selectively detected using a (2+1) resonanceenhancedmultiphoton ionization(REMPI) technique 3 . To everyone’s surprise, channels producing 0 0 ,2 1 , 2 2 states of product CH 3 were completely depleted by the reactant vibrational excitation, whilethe 1 1 /3 1 path exposed less depletion. It means the antisymmetric stretching excitation of reactantCH 4 not only exhibits no promotion to the reaction, but also restrains the rupture of the excitedbond. In other words, it hinders the overall cross section of the title reaction. This finding furthersour understanding of polyatomic reactions, and requires more experimental and theoretical workson corresponding reaction dynamics.References1 J. C. Polanyi, Science 236 (4802), 680 (1987); W. Q. Zhang, H. Kawamata, and K. P. Liu, Science 325 (5938), 303 (2009).2 G. R. Wu, W. Q. Zhang, H. L. Pan, Q. Shuai, B. Jiang, D. X. Dai, and X. M. Yang, Review of Scientific Instruments 79 (9),094104 (2008).3 W. Shiu, J. J. Lin, and K. Liu, Physical Review Letters 92 (10), 103201 (2004).71

POSTER SESSION 1 P1-15Experimental nascent rovibrational distributions of the OH(X 2 ) products ofthe O( 1 D) + CH 4 reaction at = 0.403 eV.M. Pilar Puyuelo*, Pedro Alberto Enríquez**, Iván Antón-García, F. Javier GuallarDepartamento de Química, Universidad de La Rioja.Calle de Madre de Dios, 51, 26006 Logroño. Spain.*pilar.puyuelo@unirioja.es, **pedro.enriquez@unirioja.esThe dynamics of title reaction were studied in a laser photolysis/ laser-induced fluorescence (LIF)setup employing a flow system. O( 1 D) atoms were generated by photodissociating N 2 O at 193.3 nmusing an ArF excimer laser. The quantum states of OH(X 2 , v" = 1-2, N", J", ”, ") were probed byLIF excitation spectra of the (0,1), (2,1) off-diagonal vibrational bands ( 0) of the A 2 + X 2 system, using Nd-YAG pumped tunable dye laser.The nascent rovibrational populations for the OH(X 2 , v"= 1-2) products and their surprisal plotsare collected in figure 1. The surprisal analysis of the rovibrational distributions reveals that thepopulations at v” =1 and 2 are both unimodal, in agreement with previous studies performed in ourlaboratory for v=0,1 [1] y v=2-4 [2].Figure 1. Nascent rovibrational populations of the OH(X 2 , v"= 1-2) reaction products of the O( 1 D)+ CH 4 . (upperrow) and the corresponding surprisal plots (lower row). The error bars correspond to one standard deviation.In a previous study [1], the rovibrational distribution of the v”= 0 products, was shown to bebimodal, with a linear high-N” component and a low-N” component. This behaviour was explainedwith the help of QCT calculations that revealed the presence of two different atomic level insertionreactions mechanisms: (i) non-direct insertion trajectories which lead to the formation of mainlyshort-lived (CH 3 )OH collision complexes that survive for a few vibrations and generate products withmonotonically decreasing vibrational and rotational excitation, and (ii) direct insertion and72

elimination, which generates products with an inverted vibrational distribution, in all the availablerotational states.For higher vibrational levels, it was found [2] that, although the rotational distribution for the v”= 2products were unimodal, the rovibrational distributions at v”= 3 and v”= 4 were also bimodal. Whilethe distributions high-N” component may correlate with the high-N” components observed for lowervibrational levels, the low-N” component, which amount for 1.5% and 5.6% of the total populationsapproximately at each vibrational level, that could not be explained using exclusively the ground 1 1 Aenergy surface in QCT calculations.With the results obtained for OH(v”= 1,2), presented in this poster, the experimental nascentvibrational distribution P(v”) for the OH(X 2 , v”) products of the O( 1 D) + CH4 reaction at 0,403 eVwas estimated (see table 1). These results will be interpreted in terms of the different mechanismsthat generate the reaction products, and compared with the results obtained for these reaction atdifferent collision energies or with different experimental methods[3-6].v 0 1 2 3 4P(v”) 0.56 0,15 0,39 0,05 0,37 0,07 0,20 0,03 0,04 0,01Table 1. Experimental vibrational populations for the OH(X 2 , v” = 0-4) products of the O( 1 D)+ CH 4 reaction atan average collision energy of 0,403 eV. Errors are shown as 1.AcknowledgementsThis work was supported by DGI (MCYT) through the Projects BQU2002-04269-C02-01 and CTQ2005-09334-C02-02, and by the University of La Rioja through project API 10/18.References[1] M. González, M. P. Puyuelo, J. Hernando, R. Sayós, P. A. Enríquez, J. Guallar, and I. Baños, J. Phys. Chem. A 2000, 104,521.[2] Iván Antón, Ph. D. Thesis, Universidad de La Rioja, 2005.[3] A. C. Luntz, J. Chem. Phys., 1980, 73, 1143.[4] S. G. Cheskis, A. A. Iogansen, P. V. Kulakov, I. Yu. Razuvaev, O. M. Sarkisov and A. A. Titov, Chem. Phys. Letters, 1989, 155,37[5] C. R. Park and J. R. Wiesenfeld, J. Chem. Phys., 1991, 95, 8166.[6] Gus Hancock, Marc Morrison and Mark Saunders, J. Photochem. Photobiol., A: Chem. 2005, 176, 19173

POSTER SESSION 1 P1-16Rovibrational state specific scattering distributions of theO( 1 D 2 ) + CD 4 → OD + CD 3 (v 1 , v 2 , N) reactionH. Kohguchi, Y. Ogi, T. SuzukiRIKEN, Hiroshima Univ., Kyoto Univ.In our previous study [1], we obtained unambiguous evidence for the existence of the elusiveabstraction path from the state-resolved scattering distributions of CD 3 products obtained by crossedmolecular beam ion imaging. We measured rotationally state-resolved scattering distributions of CD 3in the vibrational ground state at a collision energy (E col ) of 5.6 ± 0.8 kcal mol −1 . The observedscattering distributions were characterized by a predominant forward peak and a weakerbackscattered component, in which CD 3 (v = 0) in low rotational states exhibited discrete speeddistributions only in backscattering. The discretespeed distribution clearly implied that thecounterpart OD for backscattered CD 3 isvibrationally hot but rotationally cold. Thecharacteristic features of the backscatteredcomponent are consistent with the nearcollineardynamics in the O–D–C configurationon the excited state PES. Thus, state-resolvedmeasurements of the scattering distributionsclearly identified an elusive abstraction pathway.In the present study [2], we investigatedrotationally state-resolved scatteringdistributions of CD 3 produced in thevibrationally excited states of the CD symmetricstretching (v 1 ) and out-of-plane bending (v 2 )modes and discuss the vibrational modespecificity of the energy release in the twopathways.Figure caption. Top panels: rotationally stateselectedscattering distributions of the CD 3 (v=0)products. The S(N)-branches of the 0-0 vibronic bandwith (a) N = 3, (b) N = 5, and (c) N = 7 were employedin the measurement. The left and right halves of eachimage, respectively, show the observed 2D projectionimage and a sliced image of the 3D distribution.Middle panels: v–θ plots of the sliced image of the 3D distribution. Bottom panels: the internal energydistribution of the OD counterpart obtained from the sliced image. Black: θ = 5–60 ° (forward); blue: 60–120 °(lateral); red: 120–175° (backward).References[1] H. Kohguchi, Y. Ogi, and T. Suzuki, Phys. Chem. Chem. Phys. 10 (2008) 7222.[2] H. Kohguchi, Y. Ogi, and T. Suzuki, Phys. Chem. Chem. Phys. 11(2011)8371.74

POSTER SESSION 1 P1-17Theoretical study of the H 2 O 2 (X, 1 A) and (a, 3 A) potentialenergy surfacesDaniela V. Coelho, Carolina M.A. Rio and João Brandão*CIQA, Departamento de Química e Farmácia, Faculdade de Ciências e Tecnologia daUniversidade do Algarve, Campus de Gambelas, 8005-1 39 FARO, PortugalThe reactions of an oxygen atom in its ground ( 3 P) and first excited ( 1 D) states, resulting from theincidence of solar radiation on stratospheric ozone (Hartley band), with a water molecule play animportant role on the modelling of atmospheric chemistry and ozone depletion cycle [1]. Althoughthe first reaction occurs in a repulsive potential, the intersystem crossing between the triplet andsinglet states contributes to the overall results. These reactions, and the reaction between twohydroxyl radicals, are also relevant for the chemistry of combustion processes [2].In this communication we present two PESs for the ground singlet and first excited triplet states ofthe hydrogen peroxide, H2O2.These new DMBE H 2 O 2 PESs are based on 3x3 matrixes, to accurately reproduce all the differentdissociation channels in accordance to the Wigner-Witmer rules, namely, O( 1 D) + H2O, OH + OH, O2( 1 ∆) + H2 and H + HO2 [3] for the singlet surface and O( 3 P) + H2O, OH + OH, O2 ( 3 Π) + H2 and H + HO2for the triplet one. They have been obtained by fitting a large amount of ab initio energies computedusing the aug-ccpVTZ and aug-cc-pVQZ basis sets and extrapolated to basis set limit usingexperimental data and results from five zeta basis set at reference points[4]. They also account for theelectrostatic dipole-dipole interaction between two OH ( 2 Π) fragments and long-range interactionbetween the oxygen atom and the water molecule.A description of these PESs and preliminary results of quasiclassical trajectories [5] for the O( 1 D and3 P) + H 2 O reactions will also be present.AcknowledgmentsThis work was supported by the FCT under the PTDC/CTEATM/66291/2006 and SFRH/BD/64675/2009research projects, cofinanced by the European Community Fund, FEDER.References[1] M. Braunstein, R. Panfili, R. Shroll, and L. Bernstein, J. Chem. Phys. 122, 184307 (2005).[2] S. P. Karkach and V. I. Osherov, J. Chem. Phys. 110, 11918 (1999).[3] J. N. Murrell and S. Carter, J. Chem. Phys. 88, 4887 (1984).[4] A. J. C. Varandas, Chem. Phys. Lett 443, 398 (2007).[5] W.L. Hase, et al. QCPE Program. Indiana: Indiana University; (1996). Venus96: A general chemical dynamics computerprogram.*E-mail: jbrandao@ualg.pt75

POSTER SESSION 1 P1-18Vibrational spectroscopy to probe reactions on platinum clustersDan J. Harding, Christian Kerpal, David M. Rayner*, André Fielicke, Gerard MeijerFritz-Haber-Institut der Max-Planck-Gesellschaft,Faradayweg 4-6, Berlin 14195, GermanyE-mail:harding@fhi-berlin. mpg. de*Steacie Institute for Molecular Sciences,National Research Council, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, CanadaIsolated transition metal clusters in the gas phase and their complexes with small molecules arefrequently suggested as model systems for the study of active sites of heterogeneous catalysts. In ourexperiments we combine resonant IR excitation with mass spectrometric detection to obtain detailedsize-specific insights into the structure of the clusters and their gas-phase chemistry. The coverage ofa wide frequency range from the mid-IR to below 100 cm −1 becomes possible by using the FreeElectron Laser for Infrared eXperiments (FELIX) as an intense and tunable light source. Here wepresent vibrational spectra of small platinum clusters and their complexes with methane andhydrogen in the range from 100 to 2200 cm −1 . Comparison with spectra calculated using densityfunctional theory allows the determination of the cluster structures and investigation of the effectsof the cluster size and structure on reactivity. The IR-induced fragmentation channels provide furtherinformation about the relative barriers for different processes.76

POSTER SESSION 1 P1-19Electrostatic extraction of buffer gas cooled beamsfor studying ion-molecule chemistry at low temperaturesM. Bell, K. Twyman, C. Rennick, L. Pollum and T. P. SoftleyDepartment of Chemistry, University of Oxford,Chemistry Research Laboratory, Mansfield Rd, Oxford, UK.A newly constructed apparatus which combines buffer gas cooling with electrostatic velocityselection is described. Slow and internally cold beams of polar molecules are prepared by collisionalcooling with helium atoms in a 4 K cryogenic cell. Cold molecules are continuously extracted fromthe beams using an electrostatic quadrupole guide and the output of the guide is characterisedexperimentally for a range of helium densities and guiding electric fields. In future experiments, theguided molecules will be used to study low energy reactive collisions with trapped laser cooled ions.A Direct Simulation Monte Carlo algorithm is used to provide insight into the collisional coolingdynamics occurring within the buffer gas cell and close to the cell's exit aperture.77

POSTER SESSION 1 P1-20Towards cold ion-neutral reactions using deceleratedmolecular beamsK. Dulitz, J. M. Oldham, L. Harper, M. T. Bell and T. P. SoftleyDepartment of Chemistry, University of Oxford,Chemistry Research Laboratory, Oxford, OX1 3TA, U.K.Pulsed electromagnetic fields can be used to decelerate a beam of fast, but internally cold, moleculesor atoms from a pulsed supersonic expansion. Following the design of Meijer and co-workers, wehave constructed a Stark decelerator that is used to decelerate a seeded beam of ND3 with quantumstateselectivity and with tunable final velocities between 250 m/s and 35 m/s. The decelerator iscombined with a RF ion trap in which ions are laser- or sympathetically-cooled to milliKelvintemperatures and provide a highly localised target for the decelerated beam. A fast-opening shutterbetween the decelerator and the ion trap prevents the transmission of undecelerated molecules intothe trap chamber. We discuss progress towards the study of the charge-exchange reaction betweenXe + and decelerated ND3 molecules.We are in the process of building a second decelerator beamline for paramagnetic atoms such ashydrogen and oxygen that can be readily integrated into the existing ion trap setup. Since Starkdeceleration is not possible for these species, this 12-stage Zeeman decelerator will extend the rangeof cold ion-neutral reactions that can be studied with our ion-trap experiment.78

POSTER SESSION 1 P1-21Investigation of the collisional quenching of NO A 2 Σ + usingtime resolved FTIR emission spectroscopyG. Dunning, J. Few, G. Hancock, G. RichmondPhysical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UKE-mail: Julian.few@chem.ox.ac.ukThe collisional quenching of electronically excited nitric oxide has been studied by time resolvedFourier Transform Infrared (FTIR) emission spectroscopy. A pulsed dye laser was used to excite aroom temperature thermal sample of NO X 2 Π to specific rovibrational levels in the A 2 Σ + state, in thepresence of collisions partners such as CO 2 , N 2 O, O 2 , H 2 O and NH 3 . Collisional quenching occurs,returning the nitric oxide to the electronic ground state. FTIR emission spectroscopy was employedto probe the quenching products to obtain nascent product state vibrational distributions. The NO X2 Π was found to be formed with a high level of vibrational excitation. In addition, for most cases, areactive quenching pathway was observed. The branching ratio between the reactive and nonreactivepathways was dependant on the identity of the collision partner. [1]We present recent results on the quenching of NO A 2 Σ + by O 2 , H 2 O and NH 3 . It was found thatquenching by oxygen resulted in a remarkably high amount of vibrational excitation in the NO X 2 Π,with population observed in levels up to v = 22, when previously v = 20 had been the highestpopulated level. Preliminary investigation into the reactive pathway has shown NO 2 is formed, butthat it is not a significant channel. The quenching of NO A 2 Σ + by both H 2 O and NH 3 has a reactivechannel that results in the formation of HNO via hydrogen abstraction.We also present recent measurements of the rate constants for the quenching of NO A 2 Σ + by thenoble gases, which are slower than previously determined. [2]Acknowledgements: This work has the support of the EPSRCReferences[1] S. Gowrie, DPhil Thesis, University of Oxford, (2010).[2] J. B. Nee, C. Y. Juan, J. Y. Hsu, J. C. Yang, W. J. Chen, Chem. Phys. 300, 85 (2004).79

POSTER SESSION 1 P1-22Synthetic control of retinal isomerisation via a conical intersection:towards rhodopsin reactivity in solutionGiovanni Bassolino 1 , Matz Liebel 1 , Tina Sovdat 2 , Stephen Fletcher 2 andPhilipp Kukura 11 Department of Chemistry, The Physical and Theoretical Chemistry Laboratory, University of Oxford,South Parks Road, Oxford, OX1 3QZ, UK2 Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road,Oxford, OX1 3TA, UKThe retinal chromophore is an ubiquitous tool in nature to efficiently transform photon energy intobiological activity. The most prominent systems include the proton pump bacteriorhodopsin and thevisual pigment rhodopsin. In all cases, the primary step involves the isomerisation of thechromophore, either from all-trans to 13-cis for bacteriorhodopsin or 11-cis to all-trans in the case ofrhodopsin. The reaction speed, selectivity and isomerisation quantum yield of these processes are instark contrast to those observed for the same chromophores in solution. To date, the origin of thisbehavior has been difficult to examine experimentally and such studies have been restricted totheoretical calculations.Here, we present recent results on a synthetically modified retinal that aims to reproduce thestructure of retinal in rhodopsin in solution. We observe a dramatic decrease in the excited statelifetime simply by introducing steric strain and thereby a twist about the photochemically active11=12 double bond. These results suggest that it is indeed possible to improve access to a conicalintersection mediating ultrafast excited state decay by tuning a single nuclear coordinate, even inthe presence of hundreds of alternative degrees of freedom. They pave the way towards efficientsynthetic control of photochemical and photophysical processes.80

POSTER SESSION 1 P1-23Extending velocity-map imaging using novel detectorsEdward Wilman, Jason W. L. Lee, and Claire VallanceDepartment of Chemistry, Chemical Research Laboratory, University of Oxford,Mansfield Rd, Oxford, UKApplying the technique of velocity-map imaging (VMI) to time-of-flight mass spectrometry (ToF-MS)using novel detectors offers the potential to collect significant extra information about a moleculardissociation beyond that collected through a conventional ToF-MS experiment. A photofragmentimage acquired under velocity mapping conditions sheds light on the mechanism of formation of thefragment observed. Conventional ion detection using a microchannel plate detector coupled to aphosphor screen and CCD camera achieves mass resolution by time-gating either the channel platesor an intensifier positioned in front of the CCD to the arrival time of the desired ion. An image of thespatial distribution of ions arriving at the detector during this time slice is then acquired in a singleCCD frame. In contrast, novel detector technologies offer the ability to collect data on ion arrivalpositions and times throughout the entire time-of-flight cycle. This opens up the possibility ofrecording images of every ion mass on each time-of-flight cycle, accelerating data collection as wellas opening up new methods of study.We have investigated various high-speed imaging technologies including a framing camera (DALSAZenith), a Timepix CMOS pixel detector developed at CERN, and a novel CMOS detector (PImMS: thePixel Imaging Mass Spectrometry sensor) developed in Oxford as a collaboration between OxfordChemistry, Oxford Physics, and the Rutherford Appleton Lab. We present experimental results usingeach detector and compare their performance with that of a conventional gated CCD camera.81

POSTER SESSION 1 P1-24Electron impact ionization in imaging mass spectrometryJames N. Bull, Jason W. L. Lee, and Claire VallanceDepartment of Chemistry, Chemical Research Laboratory, University of Oxford,Mansfield Rd, Oxford, UKVelocity-map imaging has traditionally employed laser ionization methods with a limited range ofaccessible ionization energies, and has focused on quantum-state selected ionization of a singlemolecular fragment of interest. This poster outlines the development of a new imaging massspectrometer utilizing a single-crystal electron impact source in order to provide universal ionizationat any selectable ionization energy between 5 – 100 eV, with typically less than 0.25 eV energyspread over this range. Initial emphasis will be on the investigation of small amide and ester speciesthat can be considered as prototypes for the peptide bond moiety. The pulsed electron gun used forionization, together with a piezoelectric pulsed valve for molecular beam production, will allowoperation at up to kiloHertz repetition rates. When combined with new high-speed imaging sensorssuch as PImMS (the Pixel Imaging Mass Spectrometry sensor, developed in collaboration betweenthe University of Oxford and the Rutherford Appleton Laboratory), this will allow images spanningthe entire mass spectrum to be captured on each acquisition cycle. The future thrust of this projectis to develop imaging mass spectrometry methods and practices that can be applied to characterizebiomolecules in more detail than available with other current techniques.82

POSTER SESSION 1 P1-25Fast detectors in ion imaging technologiesM. Brouard 1* , A. Clark 3 , J. Crooks 3 , E. Halford 1 , L. Hill 2 , J. J. John 2 , J. Lee 1 , A. Nomerotski 2 , C. Slater 1 ,R. Turchetta 3 , C. Vallance 1 , E. Wilman 1 , B. Winter 1 and W. H. Yuen 11 Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3QZ, UK2 Department of Physics, University of Oxford, Keble Road, OX1 3RH, United Kingdom3 Rutherford Appleton Laboratory, STFC, Harwell Oxford, Didcot, OX11 0QX, UKImaging technologies using the combination of a time-of-flight mass spectrometer and a twodimensionaldetector are used in a variety of experiments in the field of physical chemistry. Recently,for example, a fast-developing field has been the use of spatial imaging mass spectrometry. However,a major limiting factor in the use of conventional charge-coupled device (CCD) cameras has been thelimitation of acquiring only one image per experimental cycle. Using detectors which are capable ofacquiring multiple images within the time-of-flight period allows the collection of multiple masses perduty cycle. This, in turn, opens up a large number of possibilities. A number of experiments usingdifferent fast detectors are presented here.*E-mail: mark.brouard@chem.ox.ac.uk83

POSTER SESSION 1 P1-26Time-‐resolved studies of σ* mediated dynamics: From biomolecules tofrustrated molecular dissociationG.M. Roberts and V.G. StavrosDepartment of Chemistry, University of Warwick, Coventry, CV4 7AL, UKThe seminal paper of Sobolewski et al., [1] identified the potential impact of 1 πσ* state drivenphotochemistry in heteroaromatic molecules. These authors postulated that via predissociation of1 ππ* states and conical intersections with the ground state, 1 πσ* states localized along X-Hcoordinates (typically X=O, N) trigger internal conversion processes which potentially contribute tothe photostability of these biomolecules. In an attempt to unravel the complex interplay betweenadiabatic vs non-adiabatic dynamics involved in σ* driven processes in excited states, we havestudied a range of biomolecules seeking to pinpoint trends in their photochemistry. The experimentsare based on time-resolved velocity map ion imaging, enabling us to gain both time and energyinformation upon the dynamics of the photodissociation process. This work gives a brief overview ofthe recent studies from our group on H-atom elimination in heteroaromatic chromophores [2, 3]and biomolecules [4] and current work on CH 3 elimination from 1 nσ* states localized along S-CH 3coordinates [5]. The results obtained point towards the seemingly ubiquitous nature of 1 πσ* and1 nσ* states in the photoexcited state dynamics of aromatic heterocycles.References[1] A.L. Sobolewski, W. Domcke, C. Dedonder-Lardeux and C. Jouvet, Phys. Chem. Chem. Phys., 4, 1093 (2002).[2] D.J. Hadden, K.L. Wells, G.M. Roberts, L.T. Bergendahl, M.J. Paterson and V.G. Stavros, Phys. Chem. Chem. Phys., 13,10342 (2011).[3] C.A. Williams, G.M. Roberts, H. Yu, N.L. Evans, S. Ullrich and V.G. Stavros, J. Phys. Chem. A, DOI: 10.1021/jp2053212.[4] A. Iqbal and V.G. Stavros, J. Phys. Chem. Lett., 1, 2274 (2010).[5] G.M. Roberts, D.J. Hadden, L.T. Bergendahl, M.J. Paterson and V.G. Stavros, submitted.84

POSTER SESSION 1 P1-27A molecular synchrotronP. C. Zieger, S. Y. T. van de Meerakker, H. L. Bethlem, A. J. A. van Roij, and G. MeijerFritz-Haber-Institut der Max-Planck-Gesellschaft,Faradayweg 4-6, Berlin 14195, GermanyWith a Stark decelerator it is possible to produce beams of cold neutral polar molecules with atunable velocity that are well suited for molecular beam scattering studies. One can load thesebeams into a molecular synchrotron; this offers particularly interesting prospects for these kinds ofscattering experiments. In principle, a storage ring allows for the confinement of multiple packets ofmolecules that repeatedly interact in a circle, thereby, significantly increasing the sensitivity ofmolecular collision experiments.We present a molecular synchrotron consisting of 40 straight hexapoles that allows thesimultaneous confinement of multiple packets moving clockwise and counter clockwise. We willexplain the operation principle of the synchrotron and present our latest experiment, wheremultiple molecular packets are confined over a flight length of one mile [1]. Recently a second Starkdecelerator beamline was built to enable the injection of multiple counter-propagating packets inthe synchrotron.These measurements epitomize the level of control that can now be achieved over molecular beamsand brings a low-energy molecular collider within close reach.References[1] P.C. Zieger, S.Y.T. van de Meerakker, C.E. Heiner, H.L. Bethlem, A.J.A. van Roij, G. Meijer, PRL 105, 173001 (2010)85

POSTER SESSION 2 P2-1NO(X)-X systems: A combined microwave and quantum studyS. Marinakis, B. J. Howard,Department of Chemistry, The Physical and Theoretical Chemistry Laboratory,University of Oxford, South Parks Road, Oxford, OX1 3QZ, UKNitric oxide (NO) molecules play a key role in atmospheric phenomena, interstellar space andcombustion. In biological systems, NO plays a significant beneficial role in a variety of processesincluding vascular relaxation, anti-tumour and anti-pathogen response, mitochondrial respiration,and it is a ubiquitous signalling molecule in the cardiovascular system (Nobel Prize in Physiology andMedicine (1998)). At higher concentrations, NO becomes toxic, and at lower concentrations is relatedwith the systematic hypotension of septic shock. However, detailed studies of NO complexes arerequired for a quantitative modelling of these media. The aim of the present work is to study thelower bound states of Rg-NO open-shell van der Waals complex using Fourier Transform MicrowaveSpectroscopy (FTMS) and Quantum Mechanical (QM) calculations.The microwave spectrum covered the range of 6.5-18.8 GHz, where a high number of notably weaktransitions were observed. A new Hamiltonian, which takes into account the open-shell nature of NOand the hyperfine structure, is used for the analysis of the experimental measurements. Two models,a semi-rigid and a dynamical one, were employed to compare the experimental results with the mostrecent ab initio predictions for the transition frequencies. The accuracy of the most recent ab initioPESs is discussed in the view of our new experimental results. Finally, KrNO is compared with thesimilar HeNO and ArNO complexes regarding the quenching of NO orbital angular momentum in thecomplex and the barrier to free orbital motion.QM close-coupling calculations have been used to study fully quantum state-resolved productdifferential rotational alignment in collisions of NO(X 2 Π 1/2 , v=0, j=0.5, f) + Kr at a collision energy of500 cm -1 , using the most recent ab initio potential energy surface of Wen et al. [J. Phys. Chem. A 113(2009) 7366]. We show for that fully quantum state-resolved differential alignment exhibits anoticeable parity-dependent behavior. The results are discussed and compared with previousexperimental and theoretical studies on NO(X) + He/Ar inelastic scattering at similar collisionenergies.Finally, we examine weak magnetic effects on the bound states of Rg-NO(X) systems.86

POSTER SESSION 2 P2-2High resolution study on high excited Rydberg H atom scattering with o-D 2Shengrui Yu, Kaijun Yuan, Jiuchuang Yuan, Dongxu Dai, Xueming YangState Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, ChineseAcademy of Sciences, Dalian, 116023, P. R. ChinaThe dynamics of Rydberg-atom (RA) collisions with atoms or molecules has been the subject ofseveral decades of study. In 2005, reactive RA scattering crossed-beam experiments on the RAreaction H*+D 2 →D*+HD have been carried out by Xueming Yang et al. 1 and by Wrede et al. 2 at thelimited angular range respectively. They both found that this reactive scattering presents strongsimilarities to the H + +D 2 →HD+D + reaction. In order to compare of these two processes in detail, aquantitative experimental picture of Rydberg H atom scattering with D 2 is still lacking relative to thetheoretical results of ionic reaction.In the present work, full quantum-state resolved scattering of a highly excited Rydberg H(n=46) atomwith D 2 (v=0, j=0) has been carried out by using high-resolution Rydberg H/D atom time-of-flightmethod at the collision energy of 0.53eV. From experimental results, both inelastic and reactivescattering are significant in this system. In H* inelastic scattering with D 2 , nuclear spin in D 2 is clearlyconserved. The differential cross sections for the D 2 product at v’=0 and 1 from inelastic scatteringshow the reverse distributed tendency: D 2 (v’=0) have obvious forward scattering and D 2 (v’=1) havebackward scattering. This experimental observation shows the same behaviour for the simplest andmost studied of all neutral–neutral collisions. Relative to inelastic scattering, only about16.85±1.69% product belongs to reactive scattering in the H (n=46)-D 2 collisions. Even though, therotational distribution of the HD products has nearly statistical rotational distribution as thetheoretical results. The total differential cross section for that reactive scattering shows obviousforward scattering what is not the same as the result of theoretical calculations which showsymmetry in forward-backward scattering directions. That disagreement between experiment andtheory suggests that there may be inherent differences between the Rydberg atom scattering andionic reaction.Reference1. C. C. Wang, G. R. Wu, S. A. Harich, H. Song, M. Hayes, R. T. Skodje, X.Y. Wang, D. Gerlich, and X. M. Yang, Phys. Rev. Lett.95, 013201(2005).2. E. Wrede, L. Schnieder, K. Seekamp-Schnieder, B. Niederjohann, and K. H. Welge, Phys. Chem. Chem. Phys. 7, 1577(2005).87

POSTER SESSION 2 P2-3Tracking the energy flow in the OH+HD-->H 2 O+D reaction:The spectator modelChunlei Xiao 1 *, Xin Xu 1 *, Shu Liu 1 , Tao Wang 1 , Wenrui Dong 1 , Tiangang Yang 1 , Zhigang Sun 1 , DongxuDai 1 , Xin Xu 2 , Dong H. Zhang 1+ , Xueming Yang 1+1 State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, ChineseAcademy of Sciences, Dalian, Liaoning, 116023, P. R. China.2 Department of Chemistry, Fudan University, Shanghai, 200433, P. R. ChinaThe H 2 + OH → H 2 O + H reaction is of great importance in combustion chemistry and interstellarchemistry. Since three of the four atoms in the system are hydrogen, it is also an ideal system forpursuing both high quality ab initio calculation of a potential energy surface and accurate quantumdynamics calculations. As a result, the reaction has become a benchmark system for four-atomreactions, in much the same way that the H+H2 reaction served for three-atom reactions.Here we report a crossed-beam scattering experiment on the title reaction by using the highresolutionand highly sensitive D-atom Rydberg tagging method [1] . The mode-specific energy disposalis found in the OH + HD H 2 O + D reaction, as shown in the OH + D 2 HOD + D reaction [2] . Most ofthe H 2 O molecule is produced with the first stretching excitation of the OH bond. Because the newlyformed OH bond is identical to the original OH bond, an intriguing question is whether the originalOH bond in the OH radical acts as a truly “spectator” in the chemical reaction. Combined with thefull-dimensional quantum wave packet calculation, we confirmed that the original OH bond serves asa spectator in the course of chemical reaction and is excited periodically after the new OH bond isformed due to the wave packet oscillation between two symmetric OH wells.References[1] L. Schnieder, K. Seekamp-Rahn, E. Wrede, K. H. Welge, J. Chem. Phys. 107, 6175 (1997).[2] B. Strazisar, C. Lin and H.F. Davis, Science 290, 958 (2000)88

POSTER SESSION 2 P2-4Theoretical dynamics study on the ClO 3 system: the Cl+O 3 , ClO+O 2 andO+OClO atmospheric reactionsO. B. M. Teixeira 1* , A. J. C. Varandas 2 and J. M. Garcia de la Vega 31 Dpto. de Química Física Aplicada, Universidad Autónoma de Madrid, 28049, Madrid, Spain. 2 Dpto.de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugale-mail: osvaldo.debarros@uam.esIn a previous study [1], we have employed the quasi-classical trajectory method and the potentialenergy surface of FM[2] to investigate the role of both Cl + O 3 and ClO + O 2 collisions in thechemistry of stratospheric ozone. In particular, the thermal rate coefficient for ozone formation hasshown an Arrhenius-type behaviour over the range of temperatures of relevance at such altitudes,while the ClO and O 2 product vibrational distributions emerging from non-reactive events resembleclosely the initial ones.In addition to Cl + O 3 and ClO + O 2 , the exoergic reaction O + OClO → ClO + O 2 is another importantcollision process in atmospheric chemistry that evolves on the same ClO3 potential energy surface.In the present work we have modified the ClO 3 many-body expansion potential energy surface [3]of FM[2] along the minimum energy path for the O + OClO reaction such as to conform withavailable kinetics data[4], while preserving a good description of the kinetics of the reaction Cl + O 3→ ClO + O 2 . A detailed trajectory dynamics study of the reaction O + OClO → ClO + O 2 fortemperatures of relevance in stratosphere ( i.e., 250 ≤ T/K ≤ 500) will are presented. Among the twoidentified formation mechanisms for ClO + O 2 , the indirect-type reaction (i.e. formation of anintermediate ClO 3 complex followed by dissociation) is favoured over the terminaloxygenabstractionone in the range of temperatures considered. These observations find support in theflash photolysis-atomic resonance fluorescence measurements[5] for the O + OClO reaction understratospheric conditions. Concerning the vibrational distributions of the product molecules,moreover, we have observed that ClO arises vibrationally colder than O 2 , especially at lowtemperatures. Thus, the O + OClO reaction leads to the formation of vibrationally excited species(especially O2) in the stratosphere, which contributes to support the use of local thermodynamicdisequilibrium when modeling the chemistry of middle atmosphere[6,7].References[1] O. B. M. Teixeira, J. M. C. Marques, and A. J. C. Varandas, Phys. Chem. Chem. Phys., 120, 2179 (2004).[2] S. C. Farantos and J. N. Murrell, Int. J. Quantum Chem., 14, 659 (1978).[3] O. B. M. Teixeira, J. M. C. Marques, and A. J. C. Varandas, Int. J. Chem. Kinet., 39, 422 (2007).[4] J. F. Gleason, F. L. Nesbitt, and L. J. Stief, J. Phys. Chem., 98, 126 (1994).[5] A. Colussi, S. P. Sander, and R. R. Friedl, J. Phys. Chem., 96, 4442 (1992).[6] A. J. C. Varandas, J. Phys. Chem. A., 108, 758 (2004).[7] A. J. C. Varandas, Chem. Phys. Chem., 6, 453 (2005).89

POSTER SESSION 2 P2-5On the role of internal energy in HS + O 2 and OH + SO bimolecular reactions.M.Y. Ballester 1a and J. D. Garrido ba Departamento de Física, ICE, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, MG,Brazilb Universidade Federal da Integração Latino-Americana, Foz de Iguaçú, PR, BrazilThe HS + O 2 and OH + SO bi-molecular collisions are studied by means of quasi- classical trajectorymethod. 1 A previously reported global potential energy function 2 was used to represent theinteractions of the HSO 2 ( 2 A) four-body system. Trajectories are calculated for different combinationsof initial rotational and vibrational quantum numbers. Reactivity is in general affected when changingany of such types of internal energy. 3–5 Models to consider the dependence of the reactive crosssection on the internal energy of the reactants are then proposed.AcknowledgmentsFinancial support from Fundaçâo de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG PEE-00985-11) and UFJF is acknowledged.References[1] W. L. Hase, MERCURY: a general Monte-Carlo classical trajectory computer program, QCPE#453. An updated versionof this code is VENUS96: W. L. Hase, R. J. Duchovic, X. Hu, A. Komornik, K. F. Lim, D.-H. Lu, G. H. Peslherbe, K. N.Swamy, S. R. van de Linde, A. J. C. Varandas, H. Wang, R. J. Wolf, QCPE Bull 1996, 16, 43.[2] M. Y. Ballester and A. J. C. Varandas, Phys. Chem. Chem. Phys. 7, 2305 (2005).[3] M. Y. Ballester, Y. O. Guerrero, and J. D. Garrido, Int. J. Quantum Chem. 108, 1705 (2008).[4] J. de Dios Garrido, M. A. C. Nascimento, and M. Y. Ballester, Int. J. Quantum Chem. 110, 549 (2010).[5] M. Y. Ballester, Y. Orozco-Gonzalez, J. de Dios Garrido, and H. F. dos Santos, J. Chem. Phys. 132, 044310 (2010).1 maikel.ballester@ufjf.edu.br90

POSTER SESSION 2 P2-6Direct angle-resolved scattering of electronically excited species: NO(A) + ArGrant PatersonSchool of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, Scotland, UKWe present a novel approach to measuring the state-to-state differential cross-sections (DCSs) forinelastic scattering of electronically excited radicals. Specifically, this proof-of-concept demonstrationfocuses on the NO(A 2 Σ + ) + Ar system. Supersonic molecular beams of NO (5% seeded in He) and Aratoms are collided at 90 degrees in a velocity-map-imaging spectrometer. In the crossing region, NOis pumped to the A 2 Σ + , v = 0, N = 0, j = 0.5 state by a pulsed nanosecond laser. After undergoingrotationally inelastic collisions with Ar during an interval of 400 ns, the rotationally state-resolvedNO(A) products are detected by (1+1') resonance- enhanced multiphoton ionization via the E 2 Σ +state. The velocity distributions of the scattered molecules are recorded using velocity-map ionimaging. This 3-colour spectroscopic approach thus allows the direct measurement of state-to-stateDCSs, and also offers a promising approach for the measurement of polarization-dependent DCSsthrough variation of the probe- laser polarisation. It overcomes the major disadvantage of initialstateselection in crossed molecular-beam experiments with ground-state species. The results of thisproof-of-concept study have recently been published as a communication [J. Chem. Phys., 134,091101 (2011)]. The article was selected as a ‘research highlight’ by the Journal of Chemical Physicsand was ranked in the top 20 most downloaded articles for the month of March 2011.91

POSTER SESSION 2 P2-7Energy transfer from translational to internal motionin impulsive ion-molecule collisionsMasato Nakamura 1 and Atushi Ichimura 21 College of Science and Technology, Nihon University, Narashinodai, Funabashi, 274-8501, JAPAN2 Institute of Space and Astronautical Science (JAXA), Yoshinodai, Sagamihara, 229-8510, JAPANShort-range repulsive forces dominate large energy transfer from the translational to internal(rotational, vibrational) motion in atom (ion)-molecule collisions. In such collisions, the interactiontime is much shorter than the rotational period of the molecule. Sometimes, the interaction timebecomes even shorter than the vibrational period. We proposed the classical hard-potential model[1] to study energy transfer due to rotational and vibrational excitations in a limit of suddencollisions. This model is a natural extension of the previously proposed classical hard-shell model [2]where only the rotational degree of freedom is taken into account. Using these two models, wehave made a systematic analysis of measured energy-loss spectra of ions scattered from moleculesin the energy range of several tens of eV [3]. There we have discussed how the shape of the energylossspectrum varies with the collision energy.Figure 1: Scaled energy loss spectra of H + (upper), Li + (middle), and Na +(lower) scattered from N 2 at collision energy of 27 [eV] and scattering angleof 90 [deg] in the centre-of-mass system. Thick-solid (thick-dashed) curvesrepresent the energy loss given by the hard-potential (hard-shell) modeland thin lines those given by the CT calculations.We also discuss systematically variation of the energy-loss spectrum with the mass of projectile. InFig. 1, we present scaled energy-loss spectra of H + , Li + and Na + scattered from N 2 molecule atcollision energy of 27 [eV] and scattering angle of 90 [deg] in the centre-of-mass system. The resultsof two models are shown together with those of the classical trajectory (CT) calculation. Through thecomparison between the models and the CT calculation, we find that the collision is sudden bothrotationally and vibrationally for H + -N 2 , rotationally sudden and vibrationally non-sudden for Li + -N 2 ,and non-sudden both rotationally and vibrataionally for Na + with N 2 . The profile of energy-lossspectra in the collision of Na + - N 2 is related to a double collision mechanism proposed by Tanuma et92

al. [4]. As a result, the collision is initially sudden but finally non-sudden as has been pointed by Beck[5]. Comparison with experiments is also given.References[1] A. Ichimura and M. Nakamura, Phys. Rev. A 69, 0227116 (2004)[2] D. Beck et al. Z. Phys. A293, 107 (1979) 299, 97(1981)[3] M. Nakamura and A. Ichimura, Phys. Rev. A 71, 062701 (2005)[4] H. Tanuma et al. Phys. Rev. A 38, 5053 (1988)[5] D. Beck, Chem. Phys. 126 (1988) 1993

POSTER SESSION 2 P2-8Fragmentation of multiply charged van der Waals clustersMasato NakamuraCollege of Science and Technology, Nihon University, Japanmooming@phys.ge.cst.nihon-u.ac.jpHere we discuss on the stability and fragmentation pattern of multiply charged van der Waalsclusters. A multiply charged cluster with charge z is stable if its size n is larger than the appearancesize n c (z). Echt et al. [1] estimated the appearance sizes for many kinds of multiply charged van derWaals clusters using the liquid drop model (LDM). Their calculation reproduced the appearancessizes of many multiply charged clusters measured in experiments, still some discrepancies has beenfound for Ne [2] and Ar [1] clusters. In their calculation, the parameters of the LDM were thosegiven through a molecular dynamics simulation at the temperature T = 40 K [3]. At this temperature,clusters are supposed to be melting (liquid-like phase) Recently, the global minimum energies ofLennard-Jones clusters have been calculated for up to size n = 1000 [4]. From these data, we have anew set of parameters for the LDM at T = 0 K. This situation corresponds to solid phase of theclusters. We calculate the appearance sizes from these global minimum energies and with using theliquid drop energy at T = 0 K. Through a comparison of these two types of calculations, we can studythe role of geometrical shell effects. Calculated appearance sizes are listed in Table 1 together withexperimental data and with the previous calculation with using LDM [1]. In general, the presentcalculations give the appearance sizes much smaller than those in the previous work. As for Arclusters, the present calculation gives in good agreement with the experimental measurements. Inmost cases, the LDM at T = 0 K gives nearly the same appearance sizes as those obtained using theshell corrected energies. As for Xen 4+ , shell effects considerably change the appearance sizes.Furthermore, due to shell effects, multiply charged clusters are not always stable even if their sizesare larger than the appearance size [5]. Detailed results are presented in [5] and [6]. We also presentwhat kind of fragment size distribution is realized.This work has been financially supported by funds for basic scientific research by College of Science,Nihon University.References[1] O. Echt et al. Phys. Rev. A38, 3236 (1988).[2] I. Maehr et al. Phys. Rev. Lett. 98, 023401 (2007).[3] C. L. Briant and J. J. Burton, J. Chem. Phys. 63, 2045 (1975)[4] D. Wales and J. Doye, J. Phys. Chem. A, 101, 5111(1997), Y. Xiang et al., J. Phys. Chem. A, 108, 3586 (2004)[5] M. Nakamura, Chem. Phys. Lett. 449, 1 (2007)[6] M. Nakamura and P.-A. Hervieux, Chem. Phys. Lett. 428, 138 (2006)94

POSTER SESSION 2 P2-9From a spectroscopic and dynamic probe of the H 2 O-H 2potential to the rotational excitation of waterYohann Scribano 1 *, Alexandre Faure 2 , A. Van der Avoird 3 , D. Nesbitt 4 , L. Wiesenfeld 21 . Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS - Université de Bourgogne, 9 Av. Alain Savary, BP47870, F-21078 Dijon Cedex2 . Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), UMR 5274 - UJF-Grenoble 1/CNRS, Grenoble, F-38041,France3 . Theoretical Chemistry, Institute for Molecules and Matrials, Radboud University, Nijmegen, Heyendaalsweg 135, 6525 AJNijmegen, The Netherlands4 . JILA, University of Colorado and National Institute of Standards and Technology and Department of Chemistry, andBiochemistry, University of Colorado, Boulder, Colorado 80309-0440* Yohann.Scribano@u-bourgogne.frThe molecular system H 2 O-H 2 is a benchmark complex for chemical physics and astrochemistryapplications. Indeed, from an astrophysical point of view this complex is very important since themain water isotopologues, H 2 16 O (hereafter H 2 O), is the third most abundant molecule in theUniverse, after H 2 and CO. Furthermore, the deuterated water isotopologues HDO and D 2 O are ofspecial importance because they can help to understand the origin of water in the interstellarmedium and its possible link with the D/H ratios observed in comets and in the oceans on theEarth. In order to interpret the observed spectra in terms of local physical conditions and relativeabundances, radiative transfer modeling is necessary which, in turns, requires the knowledge ofrates for collisional (de)excitation of water by hydrogen.In this talk, I will present in a first part the theoretical analysis of the recent potential energysurface obtained by Valiron et al. [1]. Indeed, this potential was computed using high levelelectronic structure calculations (explicitly correlated) and taking into account the intramoleculardeformation of each monomer. It has been successfully tested by several experimentaltechniques, such as differential measurements [2], molecular beam scattering [4] and pressurebroadening experiments [3], and by bound states calculations [5, 7, 6]. The second part of this talkwill be devoted to the application of this potential to inelastic scattering of deuterated water byhydrogen, with special emphasis on intramolecular geometry effects [8, 9]. Indeed, investigationof the abundance of water and its isotopologues in space is one of the main target of the HIFIheterodyne instrument aboard Herschel Space Observatory, which was launched in may 2009 andwhich has detected H 2 O, HDO and D 2 O towards star forming regions (e.g., D 2 O [10]).References[1] P. Valiron, M. Wernli, A. Faure, L. Wiesenfeld, C. Rist, S. Kedzuch, J. Noga, J. Chem. Phys. 129, 134306 (2008).[2] C.-H. Yang, G. Sarma, J.J. ter Meulen, D. Parker, G.C. McBane, L. Wiesenfeld, A. Faure, Y. Scribano, N. Feautrier, J.Chem. Phys. Communication, 133, 131103 (2010).[3] L. Wiesenfeld and A. Faure, Phys. Rev. A 82, 040702 (2010).[4] F. Belpassi, M. L. Reca, F. Tarantelli, L. F. Roncaratti, F. Pirani, D. Cappelletti, A. Faure, Y. Scribano, J. Am. Chem.Soc. 132 (37), 13046 (2010).[5] A. van derAvoird, D. J. NesbittJ.Chem.Phys. 134,044314(2011)[6] A. van der Avoird, Y. Scribano, A. Faure and D. J. Nesbitt submitted to Chem. Phys.[7] X.-G. Wang and T. Carrington J.Chem.Phys. 134, 044313 (2011)[8] Y. Scribano, A. Faure and L. Wiesenfeld, J.Chem.Phys. Communication, 133, 231105 (2010)[9] L. Wiesenfeld, Y. Scribano and A. Faure, Phys. Chem. Chem. Phys. 13, 8230 (2011).[10] C. Vastel, et al., Astron. Astrophys., 521, L31 (2010).95

POSTER SESSION 2 P2-10Driving reactivity on size-‐selected transition metal clusters:Comparing infrared and collisional activationSuzanne Hamilton, Alexander Hermes, Imogen Parry and Stuart MackenzieDepartment of Chemistry, University of Oxford,Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford, UKIn collaboration with Andre Fielicke and Gerard Meijer of the Fritz-Haber Institute, Berlin, we haverecently demonstrated that infrared-heating can be used to initiate surface chemistry on isolatedsize-selected metal clusters. 1,2 In these initial studies, nitrous oxide molecules molecularly adsorbedon rhodium clusters provided both the IR-chromophore and reactant. We have recently explored thegenerality of this approach and extended it to bimolecular reactions on cluster surfaces. Here, wereport the results of IR-driven CO-oxidation reaction on cationic platinum-oxide clusters followingabsorption via the CO stretch.We also report the results of single–collision activation studies designed to test the thermal nature ofthe IR-driven processes. These are ion cyclotron resonance studies performed in collaboration withProfessor Martin Beyer (University of Kiel, Germany). We show that both collisional activation withinert species and CO chemisorption are effective in triggering similar surface reactivity to that drivenby infrared heating. Furthermore blackbody infrared radiative dissociation (BIRD), in conjunction withmaster equation modelling, has been used to investigate the barriers to surface reactions.References1 S.M. Hamilton et al., J. Am. Chem. Soc., 132, 1448(2010)2 S.M. Hamilton et al., J. Phys. Chem. A, 115, 2489 (2011)96

POSTER SESSION 2 P2-11Hydrogen atom abstraction reactions in solution phaseStuart J. Greaves and Andrew J. Orr-EwingSchool of Chemistry, University of BristolThe dynamics of hydrogen atom abstraction reactions are studied in liquid solution using ultrafastspectroscopic methods. 1,2 Reactions are initiated by the photodissociation of a radical precursor witha short (~50 fs) UV pulse. Products are then detected with sub-picosecond time resolution using abroadband (~500 cm -1 ) IR pulse. The recorded transient IR spectra show the formation ofvibrationally excited products at early times, which relax to ground state products at late times. Bycomparing the results of our solution phase experiments with computational calculations andprevious gas phase experiments, insights into the effect of solvent on both the potential energysurface and dynamics of a reaction can be gained.1. Vibrationally quantum-state-specific reaction dynamics of H atom abstraction by CN radical in solution. S.J. Greaves,R.A. Rose, T.A.A. Oliver, D.R. Glowacki, M.N.R. Ashfold, J.N. Harvey, I.P. Clark, G.M. Greetham, A.W. Parker, M. Towrieand A.J. Orr-Ewing, Science, 331 1423–1426, (2011).2. Vibrationally quantum-state-specific dynamics of the reactions of CN radicals with organic molecules in solution. R.A.Rose, S.J. Greaves, T.A.A. Oliver, I.P. Clark, G.M. Greetham, A.W. Parker, M. Towrie, and A.J. Orr-Ewing, J. Chem. Phys.,134 244503, (2011).97

POSTER SESSION 2 P2-12Sticking of hydrogen on grapheneB. LepetitUniversité Paul Sabatier, Toulouse, FranceB. JacksonChemistry Department, University of Massachusetts Amherst, USAWe present quantum mechanical modelling results for hydrogen sticking on graphene sheets. Themodel involves a thermally averaged wavepacket description of the incoming hydrogens and webuild a semi-empirical model of graphene phonons to describe the dissipative process leading tosticking [1]. We consider low energy collision such that chemisorption is energetically forbidden andconsider only physisorption in the van der Waals potential well which is nearly 40 meV deep [2].We study the role of the substrate on the graphene properties. We first show by considering thephonon density of states that the presence of the substrate is essential to obtain a flat graphenewhich in its absence is rippled [3]. We show that this is true not only for graphene attached to thesubstrate, but also for suspended or free standing graphene, where tension from the surroundingsubstrate flattens the membrane.We then study the sticking of hydrogen for both attached and suspended graphene at 10Ktemperature. This system can be considered as prototype for sticking problems on graphene basednano-electromechanical systems (NEMS) [4], which reach high sensitivity on the measurement of amass stuck to the membrane when operated at low temperature. In addition, at such lowtemperature, desorption which may follow sticking is inefficient. We show that sticking has a highprobability at low collision energy, and that it can be enhanced by diffraction mediated selectiveadsorption for specific collision energies [5]. It decreases however at higher energy due to thedecrease of the residence time of the faster hydrogen atoms close to the membrane.References[1] “Sticking and desorption of hydrogen on graphite : a comparative study of different models”, B. Lepetit, D. Lemoine, Z.Medina and B. Jackson, J. Chem. Phys., 134, 114705 (2011)[2] “On the performance of van der Waals corrected-density functional theory in describing the atomic hydrogenphysisorption on graphite”, R.M. Ferullo, N. Domancich, and N. Castellani, Chem. Phys. Lett., 500,283 (2011)[3] “The structure of suspended graphene sheets” J. C. Meyer, A. K. Geim, M. I. Katsnelson, K. S. Novoselov, T. J. Booth andS. Roth, Nature, 446, 60 (2007)[4] “Imaging mechanical vibrations in suspended graphene sheets”, D. Garcia-Sanchez, A. M. van der Zande, A. San Paulo,B. Lassagne, P. L. McEuen and A. Bachtold, Nanoletters, 8, 1399 (2008)[5] “Quantum studies of light particle trapping, sticking and desorption on metal and graphite surfaces”, Z. Medina and B.Jackson, J. Chem. Phys., 128, 114704 (2008)98

POSTER SESSION 2 P2-13Energy transfer of highly vibrationally excited moleculesand supercollisionsHsu-Chen Hsu, Ming-Tsang Tasi, Yuri Dyakov, and Chi-Kung NiInstitute of Atomic and Molecular Sciences,Academia Sinica, Taipei, 10617, TaiwanE-mail: hsuchen@gate.sinica.edu.twCollisional energy transfer of highly vibrationally excited molecules plays an important role in gasphasephotochemical, photophysical and thermal processes and has been studied extensively byvarious methods. Among these studies, most of the experiments were performed under bulkconditions. The results are the average of the outcome of individual conditions over the entirethermal ensemble of collision molecules. However, the detailed information was washed out duringthe average. Fisk and co-workers reported the first crossed-molecular beam experiment of collisionalenergy transfer of highly vibrationally excited KBr in 1973. Surprisingly it is the only crossedmolecularbeam experiment on the energy transfer of highly vibrationally excited molecules in thepast three decades.Recently, we have studied the energy transfer of highly vibrationally excited molecules using crossedmolecularbeam/time-of-flight mass spectrometer/time-sliced velocity map ion imaging techniques.Energy transfer distributions were obtained directly from the scatterings with high energy resolution.Energy transfer mechanisms have been proposed from these studies 1-6 . The effects of initialtranslational energy, vibrational energy, rotational energy, H/D isotope, alkylation, vibrationalfrequency, and vibrational motion on energy transfer and supercollisions will be discussed.References1. C. L. Liu, H. C. Hsu, Y. C. Hsu and C. K. Ni, J. Chem. Phys. 127, 104311 (2007).2. H. C. Hsu, C. L. Liu, Y. C. Hsu and C. K. Ni, J. Chem. Phys. 129, 44301 (2008).3. C. L. Liu, H. C. Hsu, Y. C. Hsu and C. K. Ni, J. Chem. Phys. 128, 124320 (2008).4. C. L. Liu, H. C. Hsu and C. K. Ni, J. Chem. Phys. 128, 164316 (2008).5. H. C. Hsu, Y. Dyakov and C. K. Ni, J. Chem. Phys. 133, 174315 (2010).6. H. C. Hsu, M. T. Tsai, Y. Dyakov and C. K. Ni, Phys. Chem. Chem. Phys. 13, 8313 (2011).99

POSTER SESSION 2 P2-14Selective control of photodissociation in isotopic substitutedozone 18 O 16 O 16 O moleculeB K Shandilya 1 , M Sarma 2 , S Adhikari 3 , M K Mishra 1,41 Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India2 Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, India3 Department of Physical Chemistry, Indian Association for the Cultivation of Science, Jadavpur,Kolkata 700 032, India4 University of Lucknow, Lucknow 226 007, IndiaThe making and breaking of bonds is at the core of chemistry and selective control of bonddissociation is a persistent chemical dream. With the advent of ultra short high intensity lasers, theiruse for selective control of bond breaking has received much impetus and extensive attention [1].Many scenarios using single/two color UV pulses or a combination of IR+UV pulses for selectivedissociation of HOD molecule have been investigated in our group [2-8] Selective dissociation of OHand OD bonds in HOD has been facilitated by the localized nature of these bonds whosefundamental frequencies are separated by more than 1000 cm -1 and therefore the two bonds maybe excited individually. However, in most molecules, the kind of mass separation between H and Dand coupling of the light H and D atoms through a much heavier O atom is unlikely and it is thereforedesirable to investigate the applicability of the HOD based approaches to some other molecule. The18 O 16 O 16 O molecule has been studied for selective control of dissociation of the 18 O– 16 O and 16 O– 16 Obonds by Amstrup and Henriksen [9] using function pulses for IR and UV fields.Towards this end, selective cleaving of both 18 O 16 O and 16 O 16 O bonds in 18 O 16 O 16 O is achieved usingreasonably simple UV pulses to excite the 18 O 16 O 16 O molecule in its ground vibrational state ofground electronic surface (X) to the repulsive second excited (B) surface. Results obtained from ourcalculations are analyzed using population transfer between ground and excited electronic states,flux in the 18 O 16 O + 16 O and 18 O + 16 O 16 O channels and time evolution plots. Excitation using a 50 fslaser pulse with a frequency of 39119 cm −1 achieves a branching ratio 18 O 16 O + 16 O/ 18 O + 16 O 16 O =1.81 with 40% flux in the 18 O 16 O + 16 O channel and 22% in the 18 O + 16 O 16 O channel respectively. Atwo color 50 fs laser pulse with frequencies of 37985 cm -1 and 38182 cm −1 alters a branching ratio inboth the channels.References1. S. A. Rice, Nature (London) 409, 422 (2001).2. M. Sarma, S. Adhikari, and M. K. Mishra, Chem. Phys. Lett. 420, 321 (2006).3. S. Adhikari, S. Deshpande, M. Sarma, V. Kurkal, and M. K. Mishra, Radiat. Phys. Chem. 75, 2106 (2006).4. M. Sarma, S. Adhikari, and M. K. Mishra, J. Chem. Phys. 127, 024305 (2007).5. M. Sarma, S. Adhikari, and M. K. Mishra, J. Chem. Sci. 119, 377 (2007).6. M. Sarma and M. K. Mishra, J. Phys. Chem. A 112, 4895 (2008).7. M. Sarma, S. Adhikari, and M. K. Mishra, J. Phys. Chem. A 112, 13302 (2008).8. M. Sarma, S. Adhikari, and M. K. Mishra, Mol. Phys. 107, 939 (2009).9. B. Amstrup and N. E. Henriksen, J. Chem. Phys. 105, 9115 (1996)100

POSTER SESSION 2 P2-15Angular momentum orientation of the productsof the chemical reaction F + HDM. B. Krasilnikov 1 , O. S. Vasyutinskii 1 , D. de Fazio 2 , S. Cavalli 3 , V. Aquilanti 31 Ioffe Physical-Technical Institute of the Russian Academy of ScienceSt.Petersburg, Russia2 Istituto di Metodologie Inorganiche e Plasmi,CNR Sez di Roma, Rome, Italy3 Dipartimento di Chimica dell'Università, Perugia, Italye-mail: mihail.krasilnikov@gmail.comAnisotropy in the chemical reactions products attracts much interest for decades. The importance ofvector properties in reaction collision dynamics is a consequence of the fact that practically allinteractions within a reaction complex are intrinsically anisotropic and often result in electronic, orrotational anisotropy in the reaction products.We present a theoretical study of the elementary chemical reaction F + HD(v=0, j) H + DF(v’, j’),(D+HF(v’, j’)) at the reactant translational energy of 0.078 eV. The calculations were proceeded usingnew PESs known as FXZ PES with its phenomenological modifications of the entrance channel [1].The orientation and alignment angular momentum distributions of the reaction products werepresented in terms of the anisotropy-transferring coefficients c which contain all information onthe reaction dynamics [2] for the reaction channels: H+DF(v’, j’) and D+HF(v’, j’) for v’ =0..4 andj’=0..15.Angular dependence of the product orientation shows oscillations for all calculated quantumnumbers v’ =0..4 and j’=0..15 for each of the reaction channels. As shown in case of the unpolarizedreaction reagents the product orientation can differ from zero and is always directed perpendicularto the scattering plane. The main contribution to the orientation was found to be from the first four(L=1…4) anisotropy-transferring coefficients.We calculated an experimental signal for determination of the orientation (K=1 and 3) state multiplesbased on the 2+1 REMPI scheme. Three product state multipoles: 11, 31, and 33were found tocontribute to the signal. The angular momentum orientation distributions were found to be differentin the HF and DF products due to different dynamics in the corresponding reaction channels.References[1]. D. De Fazio, J. M. Lucas, V. Aquilanti, and S, Cavalli, Phys. Chem.Chem. Phys., 2011, 13, 8571 and references therein.[2]. G.G. Balint-Kurti and O. S. Vasyutinjskii, J. Phys. Chem. A, 2009, 113, 14281.KL q101

POSTER SESSION 2 P2-16Velocity-map imaging of hydroxyl: Inelastic scattering with Ar and HeS. MarinakisDepartment of Chemistry, The Physical and Theoretical Chemistry Laboratory, University of Oxford,South Parks Road, Oxford, OX1 3QZ, UKGautam Sarma, Hans ter Meulen, David H. ParkerInstitute for Molecules and Materials, Radboud University Nijmegen, Heijendaalseweg 135,6525 ED Nijmegen, The NetherlandKenneth G. McKendrickSchool of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS,United KingdomProduct-state-selective differential cross sections (DCSs) for inelastic scattering of OH(X 2 Π) with Heand Ar have been measured via a crossed-beam technique. OH was prepared in the unique X 2 Π 3/2 , v= 0, j = 1.5, f level by hexapole field selection. Products were detected state-selectively by [2+1]resonance-enhanced multiphoton ionization of OH, combined here with velocity-map imaging (VMI)for the first time. Complementary exact close-coupled quantum scattering calculations on ab initiopotential energy surfaces (PESs) were carried out. The agreement between experimental andtheoretical DCSs is generally very satisfactory for OH + Ar, but is much less good for OH + He. Thishighlights the ability of such vector measurements to identify potential shortcomings in the bestavailablePESs for such a benchmark open-shell system. Finally, a connection is made with maseremission models.102

POSTER SESSION 2 P2-17Vibrational relaxation of nitric oxide in collisions with oxygen atoms:conciliating theoretical predictions with experimentsP. J. S. B. Caridade, V. C. Mota and A. J. C. VarandasDepartamento de Química, Universidade de Coimbra3004-535 Coimbra, Portugalpedro.caridade@ci.uc.ptThe emission of infrared (IR) radiation is one of the most important cooling mechanisms of planetarythermosphere. The mid IR spectrum at 5.3 µm is dominated by the one quantum emission of NO,with the v=1 emitting levels produced by collisions with atomic oxygen [1]. The theoretical study ofsuch collisions requires at least two potential surfaces of 2 A’ and 2 A” symmetry. The 2 A’ is the wellknown ground-state of NO2 for which a global spectroscopic accurate double many-body expansionpotential energy surface is available [2], while for the 2 A” state a single-sheeted modified many-bodyexpansion surface has been reported [3]. In previous work [3], quasi-classical trajectories have beenused to characterize the dynamical process. The results at room temperature have shown thatcollisions on the 2 A” are not an effective energy transfer process, and the total rate constant for theone-quantum removal was consistent with both experimental [4] and theoretical [5] results.However, the use of such data in the global mean model proved to generate unrealistic temperatureand density structure profiles of the thermosphere [1]. This behavior could be minimized using aremoval rate constant three-time larger and a more recent experimental study [4] supported suchevidence. Using a recently calibrated 2 A” double-many body expansion PES [6] based on accurate abinitio data, the vibrational relaxation of nitric oxide has been revisited. The results conciliate thetheoretical predictions with experiments and macro kinetic modeling, showing that the contributionof the 2 A” state is by no means negligible. The rationalization of the calculated rate constant istentatively addressed.References1. R. D. Sharma and R. G. Roble, ChemPhysChem 3, 101 (2002).2. A. J. C. Varandas, J. Chem. Phys. 119, 2596 (2003).3. P. J. S. B. Caridade, V. C. Mota, J. R. Mohallem and A. J. C. Varandas, J. Phys. Chem. A 112, 960 (2008).4. J. A. Dodd, R. B. Lockwood, E. S. Hwang, S. M. Miller and S. J. Lipson, J. Chem. Phys. 111, 3498 (1999); E. S. Hwang, K.J. Castle, and J. A. Dodd, J. Geophys. Res. 108, 1109 (2003).5. J. W. Duff and R. D. Sharma, J. Chem Soc. Faraday Trans 93, 2645 (1997).6. V. C. Mota, P. J. S. B. Caridade and A. J. C. Varandas (to be submitted).103

POSTER SESSION 2 P2-18Femtosecond photoelectron imaging of multiply charged anionsD. A. Horke, A. S. Chatterley and J. R. R. VerletDepartment of Chemistry, Durham University, Durham DH1 3LE (UK)Isolated multiply charged anions (MCAs) have an intrinsic instability due to the electrostaticrepulsion between the negative charges within the molecule. On the other hand, they also exhibitkinetic stability because of the repulsive Coulomb barrier (RCB) that exists and prevents thedissociation (Coulomb explosion) of the molecule or the electron loss by tunnelling through the RCB.We use a combination of time-, frequency, and angularly resolved photoelectron spectroscopy toexplore the intrinsic absorption spectra, vertical binding energies, photoelectron anisotropies, andexcited state dynamics of MCAs. For example, we have shown that the photoelectron angulardistribution following electron loss of an aligned MCA can be predicted based on the molecularstructure and hence, the RCB anisotropy. However, the photoelectron spectra of several MCAsreveal unexpected features and a model will be presented to account for these observations.104

POSTER SESSION 2 P2-19Photodissociation dynamics of methylamineCraig MurraySchool of Chemistry, Department of Chemistry, University of Glasgow, , G12 8QQ UKJames O. Thomas, Katherine E. Lower, Thomas A.A. Oliver and Michael N.R. AshfoldSchool of Chemistry, University of Bristol, Bristol, B8 1TSAmanda S. CaseDepartment of Chemistry, University of Wisconsin-Madison, Madison WI 53706The photochemistry of methylamine following excitation to the first singlet state is remarkably richand many dissociation pathways are energetically accessible. We have used resonance-enhancedmulti-photon ionization (REMPI) spectroscopy to detect nascent radical dissociation products afterstate-selective excitation of the parent amine in the first UV absorption band. Vibrationally excitednascent CH 3 yȆ 2 A 2 radicals provide evidence of nonadiabatic dynamics in the minor C–N scissionchannel, while the detection of NH X 3 Σ – radicals as primary photoproducts is tentatively attributed toa roaming-type mechanism. Additional high-resolution H-Rydberg atom photofragment translationalspectroscopy (HRA-PTS) experiments revisiting the major aminyl H-atom loss pathway show stateselectivedissociation dynamics.105

POSTER SESSION 2 P2-19Photodissociation of iodocyclohexane in the A-band:A complete conformational analysis.D.K. Zaouris 1 , A.M. Wenge 1 , T.A.A. Oliver 1 , D. Murdock 1 , G. Richmond 2 ,G.A.D. Ritchie 2 , R.N. Dixon 1 and M.N.R. Ashfold 11 School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK2 Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road,Oxford OX1 3QZ, UK.In this work, both experimental and theoretical, results from the photodissociation of gas-phaseiodocyclohexane in the A-band (230nm>λ>305nm) are reported. Measured velocity and angulardistributions from the ground (I, 2 P 3/2 ) and spin-orbit excited (I*, 2 P 1/2 ) states of the iodine fragmentsare presented. Since this molecule exists in two conformers (axial and equatorial), a conformerspecificdissociation mechanism is discussed. These results are supported by ab initio quantumchemical calculations and I* quantum yield measurements. Finally, two simple impulsive models areused to describe, qualitatively, the pathways in which the available energy is redistributed in eachconformer.106

POSTER SESSION 2 P2-20Cold, magnetically-trapped bromine atomsWill Doherty, Jessica Lam, Chris Rennick and Tim SoftleyDepartment of Chemistry, University of Oxford,Chemistry Research Laboratory, Mansfield Rd, Oxford, UK.Photodissociation of molecular bromine near threshold produces a pair of bromine atoms that recoilalong the polarization axis of the laser. At an appropriate wavelength, the velocity vector of one ofthe atoms can be aligned to exactly oppose the molecular beam velocity; this atom will then bestopped in the lab frame. The stopped atoms are probed by delayed multiphoton ionization. Wehave constructed a 600 mK deep magnetic trap with the field minimum at the intersection of themolecular beam with the photodissociation laser. The trap is filled from the photofragment velocitydistribution, and the Br density accumulates with successive molecular beam pulses. We havedeveloped a molecular dynamics model of the bromine atoms in the magnetic trapping field,including collisions with the molecular beam backing gas and vacuum chamber background pressure.This shows that, while a fraction of the atoms are lost through collisions with xenon, sufficientnumbers are re-loaded on each shot to accumulate a steady-state density after a few seconds.107

POSTER SESSION 2 P2-21Ionization of Rydberg H atoms at metal and semiconductor surfaces.E. So, M. Dethlefsen, X. Li, S. Ganeshalingam and T. P. SoftleyDepartment of Chemistry, University of Oxford,Chemistry Research Laboratory, Mansfield Rd, Oxford, UK.When a Rydberg atom is close to a metal surface (at a distance ~ 4n 2 ) the weakly bound electron canbe transferred into the conduction band of the metal. In this poster, we present some recentexperimental results of the charge transfer of Rydberg hydrogen atoms at surfaces. We study boththe effects of the Rydberg properties and of the surface on the ionization dynamics. The effects ofthe Rydberg characteristics are studied by varying the orbital size and the polarization with respectto the surface. The effects of the surface are studied by comparing the results from a gold surface,with those of n- and p-type semiconductor surfaces. Preliminary results for the charge transfer atsemiconductor surfaces deposited with gold nano-particles are also presented.108

POSTER SESSION 2 P2-22Doppler resolved frequency modulation spectroscopy as aprobe of angular momentum polarisationin the 248 and 266 nm photolysis of ICNM. B. Crow, G. Hancock, G. Richmond and G. A. D. RitchiePhysical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, OX1 3QZ, UKE-mail: grant.ritchie@chem.ox.ac.ukWe present the results of a study into orientation and alignment of the CN fragment produced by UVphotolysis of ICN in the à band.The CN photofragment is produced either through 248 nm or 266 nm photolysis and probed in thehigh J states on the electronic A 2 - X 2 + transition; via diode laser Doppler FM spectroscopy. Thephotodissociation process involves excitation to a coherent superposition of several excited statepotential energy surfaces. The evolution of the wavepacket along two of these surfaces, the A’( 3 0+ )and A”( 1 1 ) surfaces, results in interference effects on the approach to the product asymptote. Theoutcome of the interference creates interesting alignment and orientation properties in the CNproduct. 5,6A vibrational dependence of the orientation terms was observed at both photolysis wavelengths,showing a strong orientation of the rotational angular momentum in CN = 0 products. However,we observed a near zero orientation in = 1 resulting from 248 nm photolysis and a change in signof the measured orientation parameters between = 0 at = 1 from 266 nm photolysis. Theseeffects are particularly remarkable in light of the comparable alignment between all the statesdiscussed above. 75 J.F. Black, E. Hasselbrink, J. R. Waldeck and R. N. Zare, Mol. Phys. 71, 1143 (1990)6 M. L. Costen and G. E. Hall, Phys. Chem. Chem. Phys. 9, 272 (2007)7 G. Hancock, G. Richmond, G. A. D. Ritchie, S. Taylor, M. L. Costen and G. E. Hall, Mol. Phys. 108, 1083 (2010)109

POSTER SESSION 2 P2-23Studies of gas-phase organic photochemistry using velocity-map imagingSara H. Gardiner, M. Laura Lipciuc, Edward Wilman, and Claire VallanceDepartment of Chemistry, Chemical Research Laboratory, University of Oxford,Mansfield Rd, Oxford, UKCurrently our group is developing techniques for velocity-map imaging mass spectrometry (VMI-MS).VMI-MS involves imaging all fragmentation products produced in a single dissociation event on eachtime-of-flight cycle. Multimass imaging greatly increases the rate of data collection, and will give usthe ability to investigate larger molecules than have traditionally been looked at. VMI-MS requiresuniversal ionisation of all photofragments of interest and a detector with the ability to acquireimages of each fragment on each TOF cycle. To achieve universal ionisation of the photofragmentswe have set up a VUV tripling cell to produce 118 nm light (10.49 eV) from the third harmonic of aNd:YAG laser. The 118 nm photon energy exceeds the ionisation energy of most of the organicfragments which we may want to study. With regards to detector technology, VMI-MS requires acamera which can record multiple images within a time-of-flight cycle (i.e. within a fewmicroseconds). We are collaborating with groups at the Rutherford Appleton Laboratory (RAL) andOxford Physics in the development of an event counting imaging sensor, PImMS (the Pixel ImagingMass Spectrometry sensor), which satisfies this requirement. All work to date has been undertakenusing an intensified CCD camera (Photonic Science Mini IDI), time gated to record images of each ofthe fragmentation products in turn.Here we report on the photodissociation of ethyl halide cations (C 2 H 5 X + , X = Br and I) at 355 nm. Theethyl halide cation is created when one photon of 118 nm light ionises the parent molecule. Onabsorption of an additional photon of 355 nm the cation can dissociate via one of three possible118nm355nm pathways: C2H5XC2H5XC2H5 X or C2H4HXor C2H3H2 X . The fragmentions (C 2 H + n , n=3-5) produced via each of these dissociation pathways have been individually velocitymapimaged. In the case of ethyl bromide, the ethyl cation is produced via a direct dissociation,whereas for ethyl iodide it has been postulated that this fragment ion is produced in a statisticalfashion following relaxation to the ground state of the parent ion. Further investigation continuesinto the mechanisms involved in the formation of C2H 4 and C 2H 3 .We are particularly interested in using the VMI-MS technique to reveal the dynamics of gas phasereactions which occur within mass spectrometers. Our most recent study involves the dissociation ofN,N-dimethylformamide at 193 nm. After exploring the dissociation dynamics of this system, whichis a model for a peptide bond, we plan to investigate the photodissociations of amino acids, leadingon to studies on both symmetric and asymmetric di-peptides (e.g. gly-gly and gly-cys) and eventuallytri-peptides (e.g. gly-gly-gly)). These studies will give us greater mechanistic insight into thefragmentations of the protein backbone which occur under the conditions of UV photodissociationmass spectrometry.110

POSTER SESSION 2 P2-24Non-quenching processes in OH(A) + H 2studied via Zeeman quantum beat spectroscopyMark Brouard*, Helen Chadwick, Tom Perkins, Scott Seamons and Paul StevensonDepartment of Chemistry, University of OxfordF. Javier Aoiz and Jesus CastilloDepartment of Chemistry, Complutense University, MadridBina Fu and Joel M. BowmanDepartment of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University,Atlanta, Georgia 30322, USAThe OH(A 2 + ) + H 2 system is important in combustion, atmospheric reactions, interstellar space andas a ‘benchmark’ system for diatom-diatom collisions (the 4-atom equivalent to H + H 2 ).The quenching of the excited state OH radicals – either reactively, to H 2 O + H, or to ground stateOH(X) – has been extensively studied both theoretically and experimentally. However, less work hasbeen performed on non-quenching processes, which are the focus of the present work. OH(A)radicals undergo elastic and inelastic collisions with H 2 and can remain on the excited potentialenergy surface.In this work, the rotational energy transfer (RET) and collisional depolarization cross-sections forOH(A) + H 2 collisions have been measured by Zeeman quantum beat spectroscopy (ZQBS), andcalculated using the quasi-classical trajectory (QCT) method on the recent ab initio potential energysurface of Bowman et al. The experimental data obtained in these studies provide a very stringenttest of theory, and give insights into the dynamics of the collisions.ZQBS methods have been used previously to measure collisional depolarization for collisions ofOH(A) and NO(A) with various rare gases. With the use of a monochromator, it is possible to measureelastic cross-sections resolved in spin-rotation level and also the RET and quenching cross-sections.The three-atom QCT code used previously has generally given very good agreement with experimentand with close-coupled quantum mechanical scattering calculations, and has been substantiallymodified to deal with the 4-atom case. So far, the experimental data obtained has displayed verypromising agreement with the theory.This poster presents experimental cross-sections for collisional disorientation (total and elastic) androtational energy transfer, compared to theory and to other OH(A) + X systems previously studied.The collision dynamics are discussed, together with possible directions for future study.*E-mail : mark.brouard@chem.ox.ac.uk111

POSTER SESSION 2 P2-25Alignment effects in the rotationally inelastic collisions of NO(X) + Ar:A joint theoretical and experimental studyB. Hornung 1 , H. Chadwick 1 , C. J. Eyles 1 , B. Nichols 1 , P. G. Jambrina 2 ,F. J. Aoiz 3 , S. Stolte 4 , and M. Brouard 1*1 Department of Chemistry, University of Oxford, OX1 3QZ, Oxford, United Kingdom2 Departmento de Química Física, Universidad de Salamanca, Salmanca 37008, Spain3 Departmento de Química Física, Universidad Complutense, Madrid 28040, Spain4 Laser Center and Department of Physical Chemistry, Vrije Universiteit, 1081 HV Amsterdam, TheNetherlandsRotational angular momentum alignment effects in the rotational inelastic scattering of NO(X) withAr have been investigated by means of close-coupled quantum mechanical, quasi-classicaltrajectory, and Monte Carlo hard shell scattering calculations. It has been shown that the hard shellnature of the interaction potential at a collision energy of E coll = 66meV is primarily responsible forthe rotational alignment of the NO(X) molecule after collision. By contrast, the alternating trend inthe quantum mechanical parity resolved alignment moments with final rotational state, j’ reflectsdifferences in the differential cross sections for the total NO(X) parity conserving and changingcollisions, rather than an underlying difference in stereodynamics.Fully lambda doublet resolved ion-images were collected with a hexapole state selective crossmolecular beam ion-imaging apparatus [1] using two different linearly polarised light geometries(horizontally (H), vertically (V)). The scattering angle resolved alignment moments were retrievedfrom the experimental normalised difference (V-H)/(H+V)images. The agreement is very goodbetween the experimental and the quantum mechanical lambda doublet resolved alignmentmoments [2].References[1] J. Bulthuis, J.J. van Leuken and S. Stolte, J. Chem. Phys. 91, 205 (1995)[2] M.P. de Miranda, F. J. Aoiz, L. Banares, and V. S. Rábanos J. Chem. Phys, 111, 5368 (1999)*E-mail : mark.brouard@chem.ox.ac.uk112

We wish to thank the following for their contributions towards the success of this conference:European Office of Aerospace Research andDevelopment, Air Force Office of Scientific Research,United States Air Force Research Laboratory.The journal Physical Chemistry Chemical Physicsof the Royal Society of Chemistry.Photonic Solutions: Supplier of opto-electronics tothe photonics marketLaser 2000: Advanced Solutions for PhotonicsPhotonis: Industry | Science | MedicalOerlikon: Oerlikon Leybold Vacuum UK LtdCoherent: lasers and laser-based solutionsMolecular Physics: Taylor and Francis GroupNature Chemistry: Nature Publishing Group113