TY  - UNPB
N1  - 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.
TI  - Interaction of XUV and X-ray pulses
with diatomic molecules
EP  - 185
AV  - public
Y1  - 2025/01/28/
SP  - 1
M1  - Doctoral
A1  - Mountney, Miles Elliott
ID  - discovery10203875
N2  - 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.
UR  - https://discovery.ucl.ac.uk/id/eprint/10203875/
PB  - UCL (University College London)
ER  -