aktualisiertes pdf - DPG-Tagungen
aktualisiertes pdf - DPG-Tagungen
aktualisiertes pdf - DPG-Tagungen
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Wir haben eine mikroskopische Beschreibung des gekoppelten<br />
Cluster-Matrix-Systems entwickelt. Sie basiert auf folgenden Ingredienzien:<br />
Zeitabhängige Dichtefunktionaltheorie für die Cluster-Elektronen,<br />
Kopplung an die Edelgasatome durch Pseudopotentiale, kurzreichweitige<br />
Abstoßung und einen Van-der-Waals-Beitrag. Das Modell wird an<br />
empirisch bekannte Daten der Dimere Na-Ar und Ar-Ar kalibriert.<br />
Als erste Anwendungen untersuchen wir den Einfluss der Ar-Matrix<br />
auf das Dipol-Spektrum der Cluster sowie auf die Dynamik von Laseranregungen.<br />
Im zweiten Schritt analysieren wir den Energietransport vom<br />
Cluster in die Matrix und die nachfolgende Veränderung der Matrix durch<br />
die Anregung.<br />
MO 17.8 Do 14:00 Schellingstr. 3<br />
Cluster impact dynamics — •Anna Tomsic and Christoph Gebhardt<br />
— Max-Planck-Institut für Quantenoptik<br />
We present results from classical molecular dynamics simulations of the<br />
impact of clusters of SO2 and H2O on rigid model surfaces. The clusters<br />
consist of 10 3 molecules and collide with the surface at a wide range of<br />
impact velocities. The degree of fragmentation, the internal temperature<br />
of the final fragments and the characteristics of the monomer emission<br />
can efficiently be described by scaling parameters related to the binding<br />
energy of the cluster and the impact velocity. To study the effect of the<br />
presence of a charged particle on the outcome of the collision, a Na + ion<br />
was introduced to the center of impacting water clusters. The ion typically<br />
acts as a spectator to the collision and ends up in one of the largest<br />
surviving cluster fragments. The immediate environment of the ion inside<br />
the cluster was examined, and we found that its ligand shell is rapidly exchanged<br />
during the collision by a combination of impact-induced removal<br />
of ligands and diffusion.<br />
MO 17.9 Do 14:00 Schellingstr. 3<br />
Photodetachment-Photoelektronen Spektroskopie und ZEKE-<br />
Spektroskopie an Halogen-N2O Clustern — •Martin Tschurl,<br />
Christoph Ueberfluß, Volker Distelrath und Ulrich Boesl<br />
— Institut für Pysikalische und Theoretische Chemie, TU München,<br />
85747 Garching<br />
Halogen-N2O Cluster haben ihr Vorkommen vor allem in der Stratosphäre.<br />
Da die Halogene maßgeblich am Abbau des Ozonloches mitwirken,<br />
ist das Untersuchen ihrer Cluster ein weiterer Beitrag zum<br />
Auffinden atmosphärenchemisch wichtiger Prozesse. Dabei kann mittels<br />
Photodetachment-Photoelektronen Spektroskopie (PD -PES) die Clusterstärke<br />
über die Verschiebung der Elektronenaffinität von freien Halogen<br />
zu Halogencluster bestimmt werden. Die hochauflösende Variante<br />
der PD-PES stellt die Anionen-ZEKE (zero kinetic energy) Spektroskopie<br />
dar. Mittels ZEKE Spektroskopie können selbst die niederenergetischen<br />
van der Waals Schwingungen des Cl-N2O Clusters aufgelöst werden.<br />
MO 17.10 Do 14:00 Schellingstr. 3<br />
Photodetachment-Photoelektronen Spektroskopie und ZEKE-<br />
Spektroskopie an Halogen-N2O Clustern — •Martin Tschurl,<br />
Christoph Ueberfluß, Volker Distelrath und Ulrich Boesl<br />
— Institut für Pysikalische und Theoretische Chemie, TU München,<br />
85747 Garching<br />
Halogen-N2O Cluster haben ihr Vorkommen vor allem in der Stratosphäre.<br />
Da die Halogene maßgeblich am Abbau des Ozonloches mitwirken,<br />
ist das Untersuchen ihrer Cluster ein weiterer Beitrag zum<br />
Auffinden atmosphärenchemisch wichtiger Prozesse. Dabei kann mittels<br />
Photodetachment-Photoelektronen Spektroskopie (PD -PES) die Clusterstärke<br />
über die Verschiebung der Elektronenaffinität von freien Halogen<br />
zu Halogencluster bestimmt werden. Die hochauflösende Variante<br />
der PD-PES stellt die Anionen-ZEKE (zero kinetic energy) Spektroskopie<br />
dar. Mittels ZEKE Spektroskopie können selbst die niederenergetischen<br />
van der Waals Schwingungen des Cl-N2O Clusters aufgelöst werden.<br />
MO 17.11 Do 14:00 Schellingstr. 3<br />
Photodissociation processes of Rydberg states in N2 in the<br />
exciting-photon energy ranges between 23 eV to 24.3 eV and<br />
25.6 eV to 26.7 eV — •Lutz Werner 1 , Sebastian Lucht 1 ,<br />
Stephan Klumpp 1 , Hans Schmoranzer 1 , Arno Ehresmann 1 ,<br />
Sven Kammer 2 , Sascha Sukhorukov 2 , Rüdiger Schill 2 , and<br />
Karl-Heinz Schartner 2 — 1 Technische Universität Kaiserslautern<br />
— 2 I. Physikalisches Institut Justus Liebig Universität Giessen<br />
It has been recently shown that neutral photodissociation of the<br />
O2 (c 4 Σ − u )nlλ 3 Σ − u , (v = 0,1) and the CO (4 Σ − u )nsσg Σ − u Rydberg<br />
states are state selective. They dissociate into neutral fragments where<br />
65<br />
one of the fragments is in a Rydberg state as well and where the effective<br />
principal quantum number of the Rydberg electron is conserved. N2<br />
Rydberg states (C 2 Σ + u )nsσ (v) were investigated using monochromized<br />
synchrotron radiation to clarify whether such a behavior can also be observed<br />
in N2. Dispersed fluorescence from excited NI fragments in the<br />
spectral ranges from 114 nm to 135 nm and simultaniously from 82 nm<br />
to 102 nm in the exciting-photon energy range from 23 eV to 24.3 eV and<br />
25.6 eV to 26.7 eV was investigated. The exciting photon energy range<br />
was chosen such that it lies just beneath the thresholds for dissociative<br />
ionisation into the fragments NII( 3 P) + NI( 4 S) and NII( 3 P) + NI( 2 D).<br />
In this exciting energy regions intensities from NI fragment fluorescence<br />
transitions 2p 2 ( 3 P)3s 4 P → 2p 3 4 S, 2p 2 ( 3 P)3d 2 P → 2p 3 4 S and from<br />
transitions in the VUV-region 2p 2 ( 3 P)nd and 2p 2 ( 3 P)ns were measured<br />
as functions of the exciting-photon energy with the very narrow bandwidth<br />
of 2meV.<br />
MO 17.12 Do 14:00 Schellingstr. 3<br />
Competition between Autoionization and Dissociation<br />
into neutral fragments of the O2 vibronic Rydbergstates<br />
(c 4 Σ − u )ns/ndσg<br />
3 Σ − u (v = 0,1) — •Sebastian Lucht 1 , Lutz<br />
Werner 1 , Stephan Klumpp 1 , Hans Schmoranzer 1 , Arno<br />
Ehresmann 1 , Phillip Demekhin 2 , Victor Sukhorukov 2 , Sven<br />
Kammer 3 , Sascha Mickat 3 , Rüdiger Schill 3 , and Karl-Heinz<br />
Schartner 3 — 1 Technische Universität Kaiserslautern — 2 Rostov<br />
State University of Transport Communications — 3 I. Physikalisches<br />
Institut Justus Liebig Universität Giessen<br />
The competition between autoionization and dissociation into neutral<br />
(v =<br />
fragments of the vibronic Rydberg states O2(c4Σ− u )ns/ndσg 3Σ − u<br />
0,1) has been investigated using photon-induced fluorescence spectroscopy<br />
and the simultaneous measurement of the photo ion yield. For<br />
the vibronic Rydberg states (c4Σ− u )ns/ndσg 3Σ − u (v = 1) strong features<br />
in the fluorescence wavelength region from 90 to 105 nm were observed<br />
but only weak features in the photo ion yield, indicating strong dissociation.<br />
In contrast for the vibronic Rydberg states (c4Σ− u )ns/ndσg 3Σ − u (v =<br />
0) only weak features were observed in the fragment fluorescence but<br />
strong features in the photo ion yield, indicating strong autoionisation.<br />
Experiments were performed with monochromatized synchrotron radiation<br />
with a bandwidth of ∆E = 1.5 meV where it was possible to observe<br />
single rotational branches. The experiments are compared to ab-initio<br />
calculations for the partial autoionization and dissociation widths and to<br />
the corresponding simulations of spectroscopic shape of the rovibronic<br />
branches.<br />
MO 17.13 Do 14:00 Schellingstr. 3<br />
High resolution studies of Autler-Townes effect in Na2. — •R.<br />
Garcia Fernandez 1 , A. Ekers 1 , J. Klavins 2 , L.P. Yatsenko 3 ,<br />
N.N. Bezuglov 4 , O. Kaufmann 1 , B.W. Shore 1 , M. Auzinsh 2 ,<br />
and K. Bergmann 1 — 1 FB Physik, TU Kaiserslautern. — 2 Dept. of<br />
Physics of the Latvian University, Riga. — 3 Inst. of Physics of the<br />
Academy of Sciences, Kiev, Ukraine. — 4 V.A. Fock Inst. of Physics,<br />
Univ. St.Petersburg, Russia<br />
Autler-Townes effect in a cascade scheme X 1 Σ + g → A 1 Σ + u → 5 1 Σ + g<br />
(or 6 1 Σ + g ) in Na2 molecules has been studied with high resolution using<br />
a well collimated supersonic molecular beam. A strong cw laser field<br />
couples the intermediate and the final level. The excitation spectrum obtained<br />
by scanning the weak cw probe laser over the resonance of the<br />
transition between the populated initial level and the intermediate level<br />
yields a well resolved Autler-Townes doublet. The doublets measured at<br />
different intensities and detunings of the probe and pump lasers are consistent<br />
with theoretical predictions. The experiments were performed for<br />
two combinations of rotational levels: J ′′ = 1 → J ′ = 0 → J = 1, and<br />
J ′′ = 7 → J ′ = 8 → J = 9. The former simulates a three level system,<br />
while the latter involves a multitude of mJ sublevels. The differences of<br />
the results in these two cases and the consequences of a deviation from<br />
perfect geometric alignment of the laser beams for the shape of the doublets<br />
are discussed.<br />
MO 17.14 Do 14:00 Schellingstr. 3<br />
Anomalous appearance of Autler-Townes effect due to interference<br />
with optical pumping. — •A. Ekers 1 , R. Garcia Fernandez<br />
1 , J. Klavins 2 , L.P. Yatsenko 3 , N.N. Bezuglov 4 , O. Kaufmann<br />
1 , B.W. Shore 1 , and K. Bergmann 1 — 1 FB Physik, TU Kaiserslautern,<br />
Germany. — 2 Dept. of Physics, University of Latvia, Riga. —<br />
3 Inst. of Physics of the Academy of Sciences, Kiev, Ukraine. — 4 V.A.<br />
Fock Inst. of Physics, Univ. St.Petersburg, Russia.