eprintid: 10203875 rev_number: 12 eprint_status: archive userid: 699 dir: disk0/10/20/38/75 datestamp: 2025-02-28 10:57:12 lastmod: 2025-02-28 10:57:12 status_changed: 2025-02-28 10:57:12 type: thesis metadata_visibility: show sword_depositor: 699 creators_name: Mountney, Miles Elliott title: Interaction of XUV and X-ray pulses with diatomic molecules ispublished: unpub divisions: UCL divisions: B04 divisions: C06 divisions: F60 note: Copyright © The Author 2025. 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. abstract: In this thesis, we study theoretically the angular distributions of electron escape and the process of molecular dissociation during the interaction between diatomic molecules and intense laser pulses in the ultraviolet and X-ray range. We start by demonstrating theoretically a one-to-one mapping between the direction of electron ionization and the phase delay between a linearly-polarized vacuum ultraviolet and a circularly-polarized infrared laser pulse for the N2 molecule. We compute the dipole matrix element to transition from an initial bound state to the continuum using quantum mechanical techniques. Following the release of the electron in the infrared pulse, we evolve classical trajectories. Neglecting the Coulomb potential and accounting for quantum interference, we compute the distribution of the direction and magnitude of the final electron momentum. We then streak single-photon ionization processes, driven by an X-ray pulse, in open-shell molecules. We obtain continuum molecular wavefunctions while accounting for the singlet or triplet total spin symmetry of the molecular ion. After ionization, we streak the electron dynamics using a circular infrared pulse. For a high intensity infrared pulse, we achieve control of the angle of escape of the ionizing electron. For a low intensity infrared pulse, we obtain final electron momenta distributions on the plane of the infrared pulse and compare them to the angular patterns of electron escape solely due to the X-ray pulse. Finally, we study the interaction between molecular oxygen, O2, and an extreme ultraviolet pulse. We compute potential energy curves of O2 up to O2+ 2 . We find the dissociation limits of these states and the atomic fragments to which they dissociate. We use the Velocity Verlet algorithm to account for the nuclear dynamics. Using Monte Carlo simulations which monitor the nuclear motion and electronic structure of the molecule, we obtain kinetic energy release distributions of the atomic fragments of O2. date: 2025-01-28 date_type: published oa_status: green full_text_type: other thesis_class: doctoral_open thesis_award: Ph.D language: eng primo: open primo_central: open_green verified: verified_manual elements_id: 2354626 lyricists_name: Mountney, Miles lyricists_id: MMOUN68 actors_name: Mountney, Miles actors_id: MMOUN68 actors_role: owner full_text_status: public pagerange: 1-185 pages: 185 institution: UCL (University College London) department: Physics and Astronomy thesis_type: Doctoral editors_name: Emmanouilidou, Agapi citation: Mountney, Miles Elliott; (2025) Interaction of XUV and X-ray pulses with diatomic molecules. Doctoral thesis (Ph.D), UCL (University College London). Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10203875/2/Main.pdf