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Title: Photoelectron Spectroscopy of highly oriented pyrolytic graphite using intense ultrashort laser pulses
Author: Catton, Emma Louise
ISNI:       0000 0004 2684 2302
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2010
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This thesis describes photoelectron emission measurements made at the surface of Highly Oriented Pyrolytic Graphite (HOPG) using ultrashort laser pulses. It concentrates on the observation and understanding of a new phenomenon whereby infrared laser pulses of just 1.5eV photon energy can be used to generate photoelectrons with kinetic energies of up to 80eV. Intensity dependence measurements depict a highly nonlinear excitation process and for p-polarised light observations can be explained by a high-order multiphoton excitation mechanism. Comparisons with photoelectron spectra taken using XUV pulse trains show a striking resemblance suggesting that the same final states excited by multiple IR pulses can also be reached by a single XUV photon. Interferometric autocorrelation measurements of the photoemission signal show increasingly high nonlinearity at greater photoelectron energies and a simulation of the interferometric data constructed using Optical Bloch Equations agreed with experiments showing that in the highly non-linear regime the autocorrelation shape depends almost exclusively on the nonlinearity of the excitation. XUV-IR pumpprobe measurements are also presented and the technical difficulties of such measurements discussed. Finally a novel technique of velocity map imaging of photoemission from a surface has been demonstrated for the first time at the HOPG surface.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QC Physics