%0 Thesis
%9 Doctoral
%A Mountney, Miles Elliott
%B Physics and Astronomy
%D 2025
%E Emmanouilidou, Agapi
%F discovery:10203875
%I UCL (University College London)
%P 185
%T Interaction of XUV and X-ray pulses  with diatomic molecules
%U https://discovery.ucl.ac.uk/id/eprint/10203875/
%X 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.
%Z 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.