Ultrafast measurements in condensed phase systems
File(s)
Author(s)
Greening, Daniel Benjamin
Type
Thesis
Abstract
Rapid advances in the field of ultrafast science have led to the creation of isolated attosecond light pulses and pulse trains in the vacuum ultraviolet (VUV) and extreme ultraviolet (XUV) spectral regions. This has opened the possibility for the observation of electronic processes on the attosecond time scale with the technique of attosecond photoelectron spectroscopy. With its expansion to the condensed phase, it allows the investigation of collective electronic processes on atomic length scales with unprecedented time resolution, probing dynamics such as electronic screening, plasmonic excitations and electron transport. An enhanced understanding of these processes is of importance for optoelectronics, catalysis and light harvesting.
However, due to both the experimental complexity of such measurements, and the range of possible dynamics occurring simultaneously, isolation of the contribution of a particular dynamical process to the experimental measurement is extremely challenging. New developments in the technique of attosecond photoelectron spectroscopy are therefore required.
In this thesis, I describe three developments to the attosecond photoelectron spectroscopy capability. A phase-stable two-colour source was developed, allowing for the possibility of studying the wavelength dependence of the ultrafast field response at the surface. A gas-phase demonstration of the two-colour streaking capability is presented, as well as the creation of XUV attosecond pulses of enhanced flux through a two-colour field synthesis. An experimental scheme for the direct comparison of attosecond valence photoemission from two metal films, Au and Ag, was implemented with experimental results indicating that this scheme can eliminate systematic errors arising from the Gouy phase. Utilizing the capability to produce isolated attosecond pulses at both 20 eV and 93 eV, an experiment investigating VUV-XUV photon energy dependence of attosecond photoemission from Au films is presented. Finally, possibilities for future work utilizing these developments to study the material and wavelength dependence of attosecond photoemission from surfaces are discussed.
However, due to both the experimental complexity of such measurements, and the range of possible dynamics occurring simultaneously, isolation of the contribution of a particular dynamical process to the experimental measurement is extremely challenging. New developments in the technique of attosecond photoelectron spectroscopy are therefore required.
In this thesis, I describe three developments to the attosecond photoelectron spectroscopy capability. A phase-stable two-colour source was developed, allowing for the possibility of studying the wavelength dependence of the ultrafast field response at the surface. A gas-phase demonstration of the two-colour streaking capability is presented, as well as the creation of XUV attosecond pulses of enhanced flux through a two-colour field synthesis. An experimental scheme for the direct comparison of attosecond valence photoemission from two metal films, Au and Ag, was implemented with experimental results indicating that this scheme can eliminate systematic errors arising from the Gouy phase. Utilizing the capability to produce isolated attosecond pulses at both 20 eV and 93 eV, an experiment investigating VUV-XUV photon energy dependence of attosecond photoemission from Au films is presented. Finally, possibilities for future work utilizing these developments to study the material and wavelength dependence of attosecond photoemission from surfaces are discussed.
Version
Open Access
Date Issued
2019-09
Date Awarded
2020-06
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
Tisch, John
Marangos, Jonathan
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)