FU Berlin Digitale Dissertation
Peter Backhaus : Laser Pulse induced Stabilisation of scattering Complexes Theoretische Untersuchungen zur Laserpuls-induzierten Stabilisierung von Stoßkomplexen
|Abstract| |Table of Contents| |More Information|

Abstract Up to now one of the most elementary steps in photochemical reactions, the formation of new bonds, has not been sufficiently investigated. The present work describes for the first time three--dimensional theoretical simulations of the photoassociation process where collision complexes are transferred to a bound state by means of ultrashort laser pulses. The first part describes the development of a theoretical model including both translational/vibrational and rotational degrees of freedom and the approximations which are used in the following simulations. In the second part the stabilization of scattering complexes in the electronic ground state is investigated for the case of HCl. The processes of both photoinduced association and acceleration are considered, with special emphasis on the effects caused by the finite angular momentum of the colliding atoms. It is shown that quasibound states can be used as initial states to effectively populate a selected bound state with a specific energy and a specific rotational quantum number. Moreover, predictions for atomic beam experiments are made. The third part is devoted to the stabilisation of scattering complexes in an electronically excited state for the case of the exciplex formation of Hg2 . Our simulations are connected with the experiments of Marvet and Dantus. In particular, it is shown that the experimentally measured laserpulse induced association reactions are caused by truly bimolecular reactions rather than unimolecular ones with a van der Waals precursor. For this experiment the pump-probe signals are simulated and its essential features are explained. The simulated and thermally averaged spectrum shows good qualitative agreement with the experimental data.

Table of Contents Download the whole PhDthesis as a zip-tar file or as zip-File For download in PDF format click the chapter title Titelseite und Inhaltsverzeichnis Einleitung Stabilisierung durch induzierte Emission Stabilisierung durch Absorption Methoden Das Modell Lösung des zeitunabhängigen Modells Der Wechselwirkungs-Operator Lösung des zeitabhängigen Modells Inelastische Wirkungsquerschnitte Dynamik im elektronischen Grundzustand Modell Gebundene Zustände Resonanzen Populationsdynamik Möglichkeiten der Störungstheorie Zustands-Selektivität Assoziations-Querschnitt Beschleunigungs-Querschnitt Mittelung Dynamik in elektronisch angeregten Zuständen Modell Wellenpaketdynamik Pump- Probe- Spektrum Thermische Mittelung Reflektions-Prinzip Zusammenfassung und Ausblick Dissoziationsgleichgewicht von Hg2 Literatur

More Information:
Online available:	http://darwin.inf.fu-berlin.de/1998/7/indexe.html
Language of PhDThesis:	german
Keywords:	photo association; scattering complexes; bimolecular; ultra-short laser pulses; theoretical
DNB-Sachgruppe:	30 Chemie
Date of disputation:	14-Jul-1998
PhDThesis from:	Fachbereich Biologie, Chemie, Pharmazie, Freie Universität Berlin
First Referee:	Prof. Dr. Jörn Manz
Second Referee:	Prof. Dr. Dietrich Haase
Contact (Author):	backhaus@chemie.fu-berlin.de
Contact (Advisor):	manz@chemie.fu-berlin.de
Date created:	09-Dec-1998
Date available:	10-Dec-1998

 

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