Ultrafast measurements in condensed matter
File(s)
Author(s)
Okell, William
Type
Thesis
Abstract
In this thesis I describe the development of an apparatus for performing attosecond photoelectron measurements in condensed matter, and the completion of attosecond streaking measurements on metal films using the apparatus. A commercial Ti:sapphire chirped pulse amplification laser system was used to generate 28fs, 2.5mJ pulses with a central wavelength of 790nm and a 1kHz repetition rate. These pulses were post-compressed using a hollow fibre system. The resulting few-cycle pulses had sub-4fs duration, and 0.4mJ energy. Diagnostics performed on the hollow fibre system revealed ionisation induced carrier-envelope phase fluctuations at input pulse energies in excess of 1mJ. These fluctuations were avoided for attosecond experiments by careful choice of the experimental parameters. The few-cycle pulses were used to generate isolated attosecond pulses through high-harmonic generation, in an amplitude-gating scheme. An ultra-high vacuum compatible two-part extreme-ultraviolet multilayer mirror setup was developed for attosecond streaking measurements on surfaces. The base pressure in the experimental chamber is 3 × 10^−9 mbar. Attosecond streaking measurements were performed on amorphous WO3 and polycrystalline Au, without any prior surface cleaning. The results indicate the applicability of attosecond streaking to a very general class of solid state samples. In WO3 the 4f photoemission precedes the valence photoemission by 140 ± 190as. In gold, possible signatures of plasmon dynamics were detected.
Version
Open Access
Date Issued
2014-03
Date Awarded
2014-07
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Tisch, John
Marangos, Jon
Sponsor
Engineering and Physical Sciences Research Council
Laserlab-Europe
Grant Number
EP/I032517/1
LOA001657
EP/F034601/1
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)