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Degree: PhD, Chemie und Pharmazie, 2017, Ludwig-Maximilians-Universität
Understanding light-matter interaction is important to control the electron and nuclear dynamics of quantum-mechanical systems. The present work investigates this in the form of angular dependent tunnel ionization and different control mechanisms for nuclear, electron and coupled dynamics. With the help of close collaboration with experimental groups several control mechanisms could be examined and explained. The refined methods and models for these studies can be expanded for different experiments or more general concepts. The first part of this thesis focuses on tunnel ionization as one of the fundamental quantum-mechanical light-matter interactions while the second and third part investigates the control of nuclear and electron dynamics in depth.
The angular dependent tunnel ionization of small hydrocarbons and the impact of their field dressed orbitals are researched in chapter 3. Advanced quantum chemical methods are used to explain experimental findings that could not be recognized by only looking at the Highest Occupied Molecular Orbital (HOMO). The so studied molecules show the importance to consider field dressed instead of field free orbitals to understand the light-matter interaction, to replicate experimental findings with theoretical models and to predict the behavior of different molecules. The influence of Rydberg character in virtual orbitals, that can become populated in a field dressed picture, can explain the difference in the angular dependent tunnel ionization for two similar derivates of Cyclohexadiene (CHD) and the lobed structure for C2H4 . This chapter also shows the success of adapting a previous used model for diatomic systems to polyatomic systems.
The second part (chapter 4) investigates the deprotonation and isomerization reaction of acetylene (C2H2) and allene (C3H4) and the potential control with laser pulses over theses reaction. The first control mechanism utilizes the light field to suppress the reaction barrier, which allows molecules with lower energy to undergo isomerization and therefore increase the rate of the reaction. The second scheme controls the asymmetry of the reaction, so that either the left to right or right to left isomerization is preferred. This control is exercised by directly manipulating the nuclear wave packet with the Carrier–Envelope–Phase (CEP) of the laser pulse. The mechanism relies on forming a superposition of different normal modes that are excited by different means and therefore have a phase difference. One or more normal modes are excited by the light field and get the CEP imprinted in their phase while the other important normal modes are indirectly excited by the ionization process. This enables directional control of the nuclear dynamics in symmetric molecules. The concept of forming the superposition is general enough to be used in different reactions and molecules.
In the last part (chapter 5) the control of electron dynamics with laser pulses is studied. The test case is the selective population of dressed states (SPODS) in the potassium…
Advisors/Committee Members: Vivie-Riedle, Regina de (advisor).
to Zotero / EndNote / Reference
APA (6th Edition):
Siemering, R. (2017). Light-matter interactions. (Doctoral Dissertation). Ludwig-Maximilians-Universität. Retrieved from https://edoc.ub.uni-muenchen.de/20849/
Chicago Manual of Style (16th Edition):
Siemering, Robert. “Light-matter interactions.” 2017. Doctoral Dissertation, Ludwig-Maximilians-Universität. Accessed May 20, 2018.
MLA Handbook (7th Edition):
Siemering, Robert. “Light-matter interactions.” 2017. Web. 20 May 2018.
Siemering R. Light-matter interactions. [Internet] [Doctoral dissertation]. Ludwig-Maximilians-Universität; 2017. [cited 2018 May 20].
Available from: https://edoc.ub.uni-muenchen.de/20849/.
Council of Science Editors:
Siemering R. Light-matter interactions. [Doctoral Dissertation]. Ludwig-Maximilians-Universität; 2017. Available from: https://edoc.ub.uni-muenchen.de/20849/