aktualisiertes pdf - DPG-Tagungen

wurde auch der die Anisotropie beschreibende β-Parameter geschwindigkeitsabhängig
bestimmt. Außer dem Nachweis einer Abhängigkeit des
Verzweigungsverhältnisses P(Cl ∗ )/[P(Cl) + P(Cl ∗ )] von der kinetischen
Energie der Fragmente gelang eine Bestätigung theoretischer Vorhersagen,
die eine Abhängigkeit des Verzweigungsverhältnisses vom Quantenzustand
des CSCl-Fragments erwarten lassen.
MO 12.19 Di 14:00 Schellingstr. 3
KER-selektive Auger-Elektronenemission von raumfestem N2
— •T. Jahnke 1 , L. Foucar 1 , J. Titze 1 , R. Wallauer 1 , T. Osipov
2 , E. Benis 2 , A. Alnaser 2 , O. Jagutzki 1 , W. Arnold 1 , C. L.
Cocke 2 , M. H. Prior 3 , H. Schmidt-Böcking 1 und R. Dörner 1 —
1 Institut für Kernphysik der J.W.Goethe Universität, August-Euler-Str.
6, 60486 Frankfurt am Main — 2 Dept of Physics, Kansas State University,
Cardwell Hall, Manhattan KS 66506 — 3 Lawrence Berkeley National
Laboratory, Berkeley CA 94720
Nach der K-Photoionisation von N2 kommt es nach einem Augerzerfall
in der überwiegenden Zahl der Fälle zu einer Fragmentation des
Moleküls in 2 positiv geladene Ionen. Durch koinzidente Messung der
Impulse der ionischen und der elektronischen Fragmente kann die Stellung
der Molekülachse zum Zeitpunkt des Zerfalls rekonstruiert werden,
und der Impuls des Auger-Elektrons relativ zu dieser dargestellt werden.
MO 12.20 Di 14:00 Schellingstr. 3
Direct Experimental Observation of Interatomic-Coulombic-
Decay of Neon Dimers — •T. Jahnke 1 , A. Czasch 1 , M. Schöffler
1 , S. Schößler 1 , A. Knapp 1 , M. Käsz 1 , J. Titze 1 , C. Wimmer
1 , K. Kreidi 1 , R. Grisenti 2 , O. Jagutzki 1 , U. Hergenhahn 1 ,
H. Schmidt-Böcking 1 und R. Dörner 1 — 1 Institut für Kernphysik
der J.W.Goethe Universität, August-Euler-Str. 6, 60486 Frankfurt am
Main — 2 Fritz-Haber-Institut, MPG Berlin
Using the COLTRIMS technique a direct experimental observation of
the ”Interatomic-Coulombic-Decay” (ICD) of Neon dimers has been performed.
A supersonic jet consisting of Neon atoms and small clusters is
crossed with a beam of linearly polarized light. After 2s-photoionization
of a Neon atom, an Auger decay of the atom is prohibited as the system
does not provide enough energy for the emission of an electron. In contrast
to that, for a Neon dimer an Auger decay is energetically possible,
as predicted by Cederbaum et al.: ICD occurs - relaxation of the inner
valance hole takes place as energy is transferred from the neighboring
atom.
MO 12.21 Di 14:00 Schellingstr. 3
Electron and nuclear density dynamics in model systems —
•Marco Erdmann and Volker Engel — Institut für Physikalische
Chemie, Am Hubland, 97074 Würzburg, Germany
We study the correlated electronic and nuclear quantum dynamics
in model systems which allow for a numerically exact solution of the
time–dependent Schrödinger equation. The influence of non–adiabatic
couplings on absorption spectra is investigated and temporal changes in
the electronic and nuclear densities during laser induced spectroscopic
transitions are analyzed. The time–dependent localization of electrons
within the system is characterized with the help of the ELF (electron
localization function) in the case of parallel spin and by an analogous
function for anti-parallel spin.
MO 12.22 Di 14:00 Schellingstr. 3
Energietransfer und Vibrationen in molekularen Aggregaten —
•Alexander Eisfeld und John S. Briggs — Hermann-Herder-Str.
3 D-79104 Freiburg
Seit ihrer Entdeckung vor fast 70 Jahren haben molekulare Aggregate
bestehend aus organischen Farbstoffen grosse Aufmerksamkeit auf sich
gezogen. Neben ihren mannigfaltigen Anwendungen in der Technik erregte
vor allem das bei der Aggregation entsehende schmale, rotverschobene
Absorptionsband das Interesse vieler Forscher. Schon früh wurde die Exzitonentheorie
von Frenkel benutzt um das Auftreten dieses sogenannten
J-Bandes zu erklären. Allerdings bereitete die genaue Form des Absorptionsspektrums
einige Schwierigkeiten, da die elektronische Anregung
an Vibrationen gekoppelt ist. Mit der CES-Approximation war es uns
möglich Absorptionsspektren verschiedener Aggregate herrvorragend zu
berechnen 1 . Es sollen nun der Geltungsbereich der CES-Approximation
genauer untersucht werden indem die Ergebnisse der CES Rechnungen
mit Resultaten verglichen werden die durch Diagonalisieren des zugrundeliegenden
Hamiltonoperators erziehlt wurden.
60
1 A. Eisfeld, J.S. Briggs, The J-Band of organic Dyes: Lineshape and
Coherence Length, Chem. Phys. 281, 61 (2002)
MO 12.23 Di 14:00 Schellingstr. 3
Ionization of H2 in intense laser pulses — •Erich Goll 1 , Alejandro
Saenz 2 , and Günter Wunner 3 — 1 Inst. f. Theor. Chem.,
Universität Stuttgart, D-70569 Stuttgart — 2 Inst f. Phys., Humboldt-
Universität zu Berlin, D-10117 Berlin — 3 Inst. f. Theor. Phys. 1, Universität
Stuttgart, D-70569 Stuttgart
The ionization of H2 in intense laser pulses was investigated by solving
the time-dependent Schrödinger equation in the basis of eigenfunctions
of the H2 potential. In order to describe the ionization we employed an
ionization operator, which depends on the ionization potential. This potential
corresponds to the difference between the potential curves of H2
and H + 2 and therefore varies with the distance of the nuclei. In short
pulses this leads to an effect called Lochfraß (hole biting). It means that
the wave function decreases fast in particular at those nuclear distances,
where the ionization rate is high.
Quantitative analysis shows that this effect only partly accounts for
the suppressed ionization of H2, where the ion yield for H2 is much lower
than for Ar, despite the similarity of their ionization potentials.
We have performed calculations not only for the ionization step but
also for the ensuing time evolution of the wave function in the H + 2 potential.
We find that the occupation of the vibrational states does not obey
the Franck-Condon principle.
MO 12.24 Di 14:00 Schellingstr. 3
Dynamic Transformation of Chemical Reactions of M + YX →
[MYX] → [MXY] → MX + Y — •Victor Wei-Keh Wu — Department
of Electronic Engineering, Lan-Yang Institute of Technology,
261-02 Tou-Cheng, I-Lan, Taiwan, Republic of China
It has been for ca. 80 years that chemical reaction dynamics in general
form of A + BC → AB + C has been investigated. In the mean time,
it can be well concluded: M + YX = M + HX/CH3X/DX → [MYX] →
[MXY] → MX + H/CH3/D = MX + Y : the more heavier of M (M = Ba,
K) of the reaction Ba/K + HBr, the less possible that H firstly attaches
M, or the more heavier of Y of Ba + HBr/CH3Br (Y = H, CH3, D),
the less possible that Y firstly attaches M, before MX is produced. This
means there is more or less migration, coordination of relative positions
of involved atoms during the moment of colliding or sticking together of
all atoms. The energy and momenta (translational, orbital and angular)
along the whole reaction route must be naturally conserved. How far
whether L + J = L’ + J’ can be approximately treated with L ≈ J’
should also be kept investigated. These trends may be extended for the
biomolecular reaction dynamics, specifically, for the interacting atoms
of the respective functional groups of the respective sites of interacting
biomolecules. To confront with these subjects, many assumptions
and simplifications for simulation must be done. The author is at the
same time in charge of Victor Basic Research Laboratory e. V., Bielefeld,
Germany (Email: victorbres3tw@yahoo.com.tw, http://www.unibielefeld.de/
˜ fkure, Telefax:+49-(0)521-5213339, Fax:+886-(0)3-977-
4483/Tel:-1997-ext-231(O), Tel:+886-0919-300-525(handy)
MO 12.25 Di 14:00 Schellingstr. 3
Evidence for subthermal rotational populations in molecular
ions through state-dependent Dissociative Recombination —
•L. Lammich 1 , D. Strasser 2 , H. Kreckel 1 , M. Lange 1 , H.B.
Pedersen 1 , V. Andrianarijaona 1 , S. Altevogt 1 , H. Buhr 1 , D.
Schwalm 1 , A. Wolf 1 , and D. Zajfman 2 — 1 Max-Planck-Institut für
Kernphysik, Heidelberg — 2 Weizmann Institue of Science, Rehovot, Israel
Astrophysical applications and a clean theoretical understanding call
for laboratory studies of electron–molecular ion interactions at cryogenic
temperatures (10–100K), while the ion storage rings commonly used for
such measurements are large scale, room temperature devices. A recent
experiment at the ion storage ring TSR indicates that subthermal rotational
level populations of stored molecular ions have been prepared by
continuous inelastic electron interactions.
Variations in the rate coefficient α for Dissociative Recombination of
D2H + ions with low energy electrons were observed over long storage
times, and could be attributed to changes in the rotational level distributions
of the stored ions. The comparison of data taken for different
settings of the merged electron and ion beams show that, besides the
coupling to the surrounding 300K blackbody radiation, electron interactions
can reduce the rotational excitations in the molecular ion beam.