Strong field ionization and probing of nonadiabatic dynamics in water
Abstract/Contents
- Abstract
- Intense, ultrafast laser fields can be useful tools for studying the electronic structure of molecules. Electronic structure can be studied via ionization, where the strong laser field can preferentially interact with electrons based on their binding energies and spatial orbital geometries. Strong fields can also induce nuclear motion during the ionization process. The effect that nuclear geometry has on the electronic structure will affect how strong field ionization occurs, enhancing the ionization rates at special geometries. In this thesis, I study the strong field ionization of molecular water. The goal of this study is to place the strong field multiple ionization of water among existing theories and experiments on enhanced ionization. The strong field ionization experiments in this work use intense, 800nm laser pulses with 40 fs pulse duration. Dissociation channels from the dication, trication, and tetracation are studied using the ion coincidence technique. This allows for detailed analysis of the enhanced ionization geometries. By analyzing all two and three body fragmentation channels from each isotope of water, I am able to differentiate different ionization pathways leading to the observed channels. It is found that enhanced ionization proceeds primarily from a nearly linear, symmetrically elongated molecule. Furthermore, alignment of the laser polarization parallel to the H-H bond seems to be the preferred configuration for enhanced ionization. It is shown that much of this alignment dependence is due to dynamic alignment effects that are much stronger when the molecule is linear. The electronic structure of water is also studied in the context of nonadiabatic coupling. Nonadiabatic coupling in light molecules such as water is commonplace, where two electronic states can be coupled by vibrational motion near points of degeneracy in the potential energy landscape. In this work, strong fields are used to probe an ultrafast dissociation process in neutral water where the dissociation only occurs due to nonadiabatic coupling between an excited electronic state and the ground state. The strong field probe adds an additional coupling between the two states, and as a result affects the dynamics of the dissociation channel. The effect of changing the strong field probe wavelength is investigated, as this changes the points of effective strong field coupling between the two electronic states. It is found that the dissociation is most affected when shorter strong field wavelengths are applied. This is shown to be mostly due to the effects of coupling to an intermediate state that is not involved in the field free dissociation dynamics.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2019; ©2019 |
| Publication date | 2019; 2019 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | McCracken, Gregory Alan |
|---|---|
| Degree supervisor | Bucksbaum, Philip H |
| Thesis advisor | Bucksbaum, Philip H |
| Thesis advisor | Martinez, Todd J. (Todd Joseph), 1968- |
| Thesis advisor | Schleier-Smith, Monika |
| Degree committee member | Martinez, Todd J. (Todd Joseph), 1968- |
| Degree committee member | Schleier-Smith, Monika |
| Associated with | Stanford University, Department of Applied Physics. |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Gregory A. McCracken. |
|---|---|
| Note | Submitted to the Department of Applied Physics. |
| Thesis | Thesis Ph.D. Stanford University 2019. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2019 by Gregory Alan McCracken
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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