Hadjipittas, Antonis;
(2024)
A theoretical investigation of the
interaction of high-energy lasers with
atoms and molecules.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
When high-energy pulses interact with atoms or molecules, they ionise inner electrons leaving the system in an unstable state. Following such ionisations, the system decays via one or more Auger processes until it reaches a stable state. The interplay between photoionisations and Auger decays leads to a plethora of pathways that can take the system to its final state. In this thesis we theoretically investigate the interactions of high-energy lasers with atoms and molecules. Regarding atoms, we study the interaction of xenon and argon with attosecond pulses and attosecond pulse trains respectively, by calculating the photoionisation cross sections and Auger decay rates for all energetically allowed transitions. We then employ rate equations for xenon and Monte-Carlo simulations for argon to record the final ion yields and pathways. We compare our ion yields with experiment and use the pathways to gain insight about their formation. For both systems, we investigate the effect that two sequential photoionisations and direct multi-photon absorptions have on the formation of Xe4+ and Xe5+ for xenon, and Ar2+ and Ar3+ for argon. When investigating such interactions with molecules, nuclear distance needs to be considered. Nuclear distance dictates dissociation and influences orbital wavefunctions, which in turn affect photoionisation and Auger decay calculations. We use three pre-existing techniques and introduce a fourth one to accurately produce potential energy curves for ions up to N24+. We publish a code that automatically produces these potential energy curves, as well as the molecular orbital wavefunctions at different nuclear distances. The code can be adjusted to calculate the potential energy curves of different molecules and with more than four electrons missing, making it an ideal tool for future research of such interactions.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | A theoretical investigation of the interaction of high-energy lasers with atoms and molecules |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2023. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10186418 |
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