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Multi-photon cross sections of helium-like ions under soft XUV fields

Hanks, William (2017) Multi-photon cross sections of helium-like ions under soft XUV fields. Master of Science thesis, Dublin City University.

One-, two- and three-photon l-partial ionization cross sections from the ground state of the following helium-like atoms/ions: He, Li+, Ne8+ and Ar16+ are presented in this thesis. The expressions for the cross sections are based on the lowest-order perturbation theory for the electric eld while the calculations are made with the use of an ab-initio code using a conguration-interaction method. Two-electron eigenstates are expanded on the corresponding one-electron eigenstate basis which are expressed as a set of nonorthogonal B-spline polynomials in a nite interval. The dipole matrix elements, used to compute the cross-sections, are calculated in two gauges: length and velocity, and they generally have good relative agreement granting the results a degree of condence. It was found that cross sections are dominated by photo-resonance peaks as well as by peaks associated with two-electron excitation autoionizing resonances. It is observed that in the two-photon cross sections (in the non-resonant regions) the 1D channel overwhelms the 1S one. The general trend of decreasing cross sections with increasing atomic number (Z) of the target (i.e. from He to Ar16+) is observed.
Item Type:Thesis (Master of Science)
Date of Award:November 2017
Supervisor(s):Nikolopoulos, Lampros and Costello, John T.
Uncontrolled Keywords:Atomic Physics; non-linear laser atom interactions
Subjects:Physical Sciences > Lasers
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Physical Sciences
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 License. View License
ID Code:21985
Deposited On:10 Nov 2017 09:58 by Lampros Nikolopoulos . Last Modified 13 Dec 2019 13:59

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