Eighth Condensed Phase and Interfacial Molecular Science (CPIMS)

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different kinds of structures. Our study confirms that only one out of several possible structures is obtained. In the case of W3O5 − getting oxidized to W3O6 − and releasing H2, our novel observation is that the geometry of the W3O6 − obtained after oxidation is considerably different from the geometry of the lowest-energy isomer of W3O6 − . Our recent mechanistic discovery of the reactivity-induced fluxionality in transition metal oxide clusters [Refs 2, 7] has been invaluable to unearth these significant results. C. Computational studies of molybdenum sulfide versus molybdenum oxide clusters Molybdenum and tungsten sulfides have been proved to be efficient hydrogenation and desulfurization catalysis. Several instances can be found in the literature where chemical processes of hydrogen evolution are significantly improved by the use of Mo or W sulfides as catalysts [Zong, X.; Yan, H. J.; Wu, G. P.; Ma, G. J.; Wen, F.Y.; Wang, L.; Li, C. J. Am. Chem. Soc. 2008, 130, 7176]. To understand the role of sulfides and to compare/contrast them with oxides, we have conducted a detailed computational investigation on the water reactivity of M2S4 – and M2S5 – clusters (M = Mo, W). Prior to studying reactivity, we first investigated all possible geometric and electronic structures of M2Sn – (n=2-6). We determined that all the metal sulfides have doublet electronic states in their lowest energy isomer except for M2S4 – , which have quartet ground states. The lowest energy isomers for Mo and W sulfides typically have more bridging sulfide bonds than the corresponding number of bridging oxide bonds in the oxides, a consequence of the M-S-M bonds being less strained than M-O-M bonds. Study of chemical reactivity of metal sulfides with water has been initiated with M2S4 – and M2S5 – clusters. We propose several competitive energetically favorable reaction pathways which lead to the evolution of hydrogen. Selectivity in initial water addition and subsequent proton movement are found to be the key steps in all the proposed reaction channels. Initial adsorption of water is most favored involving terminal sulfur atom in M2S5 – isomers whereas the most preferred orientation of water addition involves bridging sulfur atom in case of M2S4 – isomers. In all the H2 elimination steps, the interacting hydrogen atoms involve a metal hydride and a metal hydroxide (or thiol) group. H2 elimination step involving a thiol and a hydroxyl group has a higher barrier. For all the reaction pathways, Mo2Sn � always has a relatively higher barrier than the W analogue. Reactions of M2S4 – and M2S5 – clusters with water are exothermic and can undergo reactions with water to liberate H2 with low barriers. D. Reactions between transition metal oxide cluster anions and simple alcohols An important outcome of the computationally determined MxOy � + H2O reaction pathways was the role of H-mobility. One of the ways to test these reaction pathways is to perform reactivity studies between the transition metal oxide clusters and alcohols, which, in addition to adding two additional distinct chemical bonds, present the limited mobility of the alkoxy moiety. Furthermore, there are economic motives for finding non-precious metallic catalysts for use to treat fuel alcohol emissions. Preliminary studies on the 186 WxOy � + MeOH and 186 WxOy � + EtOH reactions have been completed, with representative results shown in Figure 4. While the kinetic analysis is in the early stages, dialkoxy products are the most significant products observed, which most likely accompany H2 production with the addition of two alcohols. III. Future Plans 400 450 500 550 600 A strength of the research program is the synergistic interplay between theory and experiment. Our target is to achieve a generalized description of the chemical reactivity of the transition metal oxides resulting in H2 liberation. Work towards this end involves studying the feasibility of H2 liberation from 97 186 - W2O4 186 - W2O5 186 - W2O 4 186 - W2O 5 186 - W2O6 - + EtOH 186 W2 O 5 186 - W2O7 186 - W2O 6 186 - 186 - W2O W2O + MeOH 7 5 186 W2O (CH O) - 186 - 4 3 2 W2O 8 - + EtOH 186 W2 O 6 - W O 2 y - W O + Ethanol 2 y 186 - W2O C H 7 4 10-11 186 - W2O C H 8 4 10-11 - W O 2 y - W O + Methanol 2 y 186 - W2O C H 8 2 5-7 186 - W2O C H 8 2 5 400 450 500 550 600 Mass/charge (amu/e - ) Figure 4. Mass spectra of ditungsten oxo clusters prior to (black trace) and after exposure to an alcohol. 186 W2 O 5 (CH 3 O) 2 -
each of the intermediates obtained in the fluxionality pathway of the clusters in the reactions of ammonia, water, and hydrogen sulfide. Other newer directions include the study of alcohol reactivity with the Mo/W oxide clusters with the view of better understanding the energetically relevant process of alcohol oxidation. Temperature-dependence studies of reaction kinetics, which will allow a direct benchmarking of calculated reaction barriers, are planned to commence in Fall, 2012. Metal sulfide cluster structure and reactivity studies will also be initiated. Independently controlled two-reagent reactivity studies (e.g., MoxOy − + CO2 + H2) will be done in an effort to model full-cycle processes. Further, with the recent approval of a supplemental equipment grant, the resonant two-photon detachment technique will be applied to clusters and complexes to probe the role of photoexcitation in reactivity. IV. References to publications of DOE sponsored research that have appeared in 2009�present or that have been accepted for publication 1. "Properties of Metal Oxide Clusters in non-Traditional Oxidation States," J. E. Mann, N. J. Mayhall and C. C. Jarrold, Chem. Phys. Lett. 525-6, 1-12 (2012). 2. “Fluxionality in the Reactions of Transition-Metal Oxide Clusters: The Role of Metal, Spin-state and the Reacting Small Molecule,” R. O. Ramabhadran, E. L. Becher, III, A. Chowdhury, and K. Raghavachari, J. Phys. Chem. A 116, 7189-7196 (2012). 3. “Study of Nb2Oy (y = 2-5) anion and neutral clusters using photoelectron spectroscopy and DFT calculations," J. E. Mann, S.E. Waller, D.W. Rothgeb and C. C. Jarrold, J. Chem. Phys. 135, 104317 (2011). 4. “Structures of trimetallic molybdenum and tungsten suboxide cluster anions," D. W. Rothgeb, J. E. Mann, S. E. Waller and C. C. Jarrold, J. Chem. Phys. 135, 104312 (2011). 5. “Molybdenum Oxides versus Molybdenum Sulfides: Geometric and Electronic Structures of Mo3Xy � (X = O, S and y = 6, 9) Clusters,” N.J. Mayhall, E.L. Becher, A. Chowdhury, and K. Raghavachari, J. Phys. Chem A, 115, 2291-2296 (2011). 6. “Resonant two-photon detachment of WO2 � ,” J.E. Mann, S.E. Waller, D.W. Rothgeb and C.C. Jarrold, Chem. Phys. Lett. 506, 31-36 (2011). 7. “Proton Hop Paving the Way for Hydroxyl Migration: Theoretical Elucidation of Fluxionality in Transition- Metal Oxide Clusters,” R.O. Ramabhadran, N.J. Mayhall, and K. Raghavachari, J. Phys. Chem. Lett. 1, 3066- 3071 (2010). 8. “Electrochemistry of Substituted Salen Complexes of Nickel(II):Nickel(I)-catalyzed Reduction of Alkyl and Acetylenic Halides,” M. P. Foley, P. Du, K. J. Griffith, J. A. Karty, M. S. Mubarak, K. Raghavachari, and D. G. Peters, J. Electroanal. Chem. 647, 194-203 (2010). 9. “Electrochemical Reduction of 5-Chloro-2-(2,4-Dichlorophenoxy)Phenol (Triclosan) in Dimethylformamide,” K. N. Knust, M. P. Foley, M. S. Mubarak, S. Skljarevski, K. Raghavachari, and D. G. Peters, J. Electroanal. Chem. 638, 100-108 (2010). 10. “H2 production from reactions between water and small molybdenum suboxide cluster anions,” D.W. Rothgeb, J.E. Mann, and C.C. Jarrold, J. Chem. Phys. 133, Article 054305 (2010). 11. “CO2 reduction by group 6 transition metal suboxide cluster anions,” E. Hossain, D.W. Rothgeb, and C.C. Jarrold, J. Chem. Phys. 133, Article 024305 (2010). 12. “Electronic structure of coordinatively unsaturated molybdenum and molybdenum oxide carbonyls,” E. Hossain and C. C. Jarrold, J. Chem. Phys. 130, 064301 (2009). 13. “Unusual products observed in gas-phase WxOy � + H2O and D2O reactions,” D. W. Rothgeb, E. Hossain, A. T. Kuo, J. L. Troyer, C. C. Jarrold, N. J. Mayhall, and K. Raghavachari, J. Chem. Phys. 130, 124314 (2009). 14. “Water reactivity with tungsten oxides: H2 production and kinetic traps,” N. J. Mayhall, D.W. Rothgeb, E. Hossain, C. C. Jarrold and K. Raghavachari, J. Chem. Phys. 131, Article 144302 (2009). 15. “Termination of the W2Oy � + H2O/D2O → W2Oy+1 � + H2/D2 reaction: Kinetic versus thermodynamic effects,” D. W. Rothgeb, E. Hossain, N. J. Mayhall, K. Raghavachari, and C. C. Jarrold, J. Chem. Phys. 131, Article 144306 (2009). 98
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Eighth Condensed Phase and Interfac
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Potential energy landscape of the (
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Agenda
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Session III Chair: Jay A. LaVerne,
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Table of Contents
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Transition Metal-Molecular Interact
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Ultrafast Electron Transport across
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CPIMS Principal Investigator Abstra
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VUV LDPI image of a polymer photore
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Publications based on DOE support (
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entirely quenched, presumably due t
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Future Plans In addition to the TiO
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The relative path indexes of the ur
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We have recently carried out molecu
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have been obtained with γ-rays sug
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Two novel plasma devices have been
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(Figure 2) can be adsorbed exclusiv
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3. Future Plans Our planned work de
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Figure 1: Snap shots from molecular
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6. Varilly, P., A. J. Patel and D.
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hypothesis that delocalized charges
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Efforts will be made to observe ele
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Photochemistry and Solvation Dynami
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complementary to work we have carri
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The Co3O4 films for the optical pum
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chamber will allow us to heat the s
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calculations. Additional PMF calcul
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the gas solute first needs to cross
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laser system, which is an infrared
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Publications (10/1/2009-present) fo
Page 61 and 62: interest are: (i) What is the diffu
Page 63 and 64: and anilino groups attached to the
Page 65 and 66: had been formed. This coincides wit
Page 67 and 68: Figure 1. (A) Simplified bR photocy
Page 69 and 70: Figure 4. Photocurrent density of b
Page 71 and 72: single-file diffusion and cannot ca
Page 73 and 74: PUBLICATIONS SUPPORTED BY USDOE CHE
Page 75 and 76: arrangement. However, the hydrogen
Page 77 and 78: (5) “Water Dynamics in Salt Solut
Page 79 and 80: from high- energy x-ray diffraction
Page 81 and 82: concentrated aqueous solutions. The
Page 83 and 84: molecule’s center of mass, or alt
Page 85 and 86: Moreover, SHG studies by Saykally
Page 87 and 88: The effective fragment potential (E
Page 89 and 90: 10. D.D. Kemp, J. Rintelman, M.S. G
Page 91 and 92: temperature dependent, equilibrium
Page 93 and 94: mimicking real organic photovoltaic
Page 95 and 96: 100 kHz amplifier, SE-FSRS was succ
Page 97 and 98: photovoltaics will be explored via
Page 99 and 100: for laser surface reactions to thes
Page 101 and 102: This is a significant advantage of
Page 103 and 104: the STM, which might underlie the u
Page 105 and 106: Future Plans: Figure 3. One and two
Page 107 and 108: methane molecule and a lattice atom
Page 109 and 110: eactive than the Ni, experiment sug
Page 111: Fig. 1. PE spectra of M3Oy � (M =
Page 115 and 116: a regime where each solvent molecul
Page 117 and 118: observables that arise from subtle
Page 119 and 120: total potentials. One can see from
Page 121 and 122: Our calculations have shown that ch
Page 123 and 124: our understanding of structure and
Page 125 and 126: viscosity, η, are inversely relate
Page 127 and 128: photodissociation of the metal - NO
Page 129 and 130: from a Ru 2p3/2 orbital to an orbit
Page 131 and 132: Integrated O 2 PSD (ML) Integrated
Page 133 and 134: anisotropy in the structure of the
Page 135 and 136: XPS studies have been performed on
Page 137 and 138: Publications with BES support since
Page 139 and 140: MLCT (metal to ligand charge transf
Page 141 and 142: molecule-metal interface without a
Page 143 and 144: observe the predicted effects, whic
Page 145 and 146: (4*) Lymar, S. V.; Schwarz, H. A. J
Page 147 and 148: (τ .820 ns), but we have not been
Page 149 and 150: B. Photodissociation spectroscopy o
Page 151 and 152: oth BLYP and PBE. Our results have
Page 153 and 154: Publications from BES support (2010
Page 155 and 156: understanding of factors that contr
Page 157 and 158: Our talk will discussion our initia
Page 159 and 160: Figure 1 shows the band structure o
Page 161 and 162: likely to also occur in low coordin
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These results are promising indicat
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This page is intentionally left bla
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method recently developed by Prende
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and coordination regions. A differe
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two ions I - [3] and IO3 - [7]. One
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"Probing the Hydration Structure of
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world-wide scientific user base sup
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10) C. Zhang, M.E. Grass, A.H. McDa
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produce the nanoparticles needed fo
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step as a symmetry-breaking templat
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work provides what we believe in th
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Selected publications acknowledging
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2. Optical Stark study of PtF (Acce
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Figure 4. The Q(3.5) line of the [1
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In marked contrast to the selective
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y depositing cobalt onto copper sin
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Carlo calculations, we have carried
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approach on a model phenol-amine pr
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We performed pump-probe experiments
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15. “A phenomenological approach
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may be initially produced in a non-
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4. Inelastic scattering of hydrogen
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Using QM/MM free energy methods we
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gas phase using electrospray ioniza
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order of Li + > Na + > K + for comp
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2. MM Meyer, XB Wang, CA Reed, LS W
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Technical Approach and Progress to
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Ionic liquid synthesis and characte
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Studies of structure and reaction d
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structure theory that include elect
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9. S. Pandelov, J. C. Werhahn, B. M
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pulse duration is a few times longe
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Figure 1 (Left) The HOMO and LUMO e
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slightly preferable in energy, the
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Participant List Dr. Musahid Ahmed
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Professor Kenneth Eisenthal Columbi
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Dr. Ireneusz Janik Notre Dame Radia
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Professor Eric Potma University of
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Dr. James Wishart Brookhaven Nation
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Eighth Condensed Phase and Interfacial Molecular Science (CPIMS)

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