Electron Sources and Column Components for Ultrafast Electron Microscopy
thesisposted on 01.11.2017 by Benjamin L Rickman
In order to distinguish essays and pre-prints from academic theses, we have a separate category. These are often much longer text based documents than a paper.
Ultrafast Electron Microscopy (UEM) is a promising new research instrumentation for the material sciences that is targeted towards improving the combined spatial and temporal resolution of measurement techniques. The applicability of UEM hinges on the quality of the pulsed electron source generated from a laser-driven photoelectron gun. Detailed knowledge of the photoemission mechanism provides a correlation between the characteristics of the photocathode and pulsed electron beam and therefore a path towards the ideal photocathode material. Improvement of this critical component will contribute to many fields where pulsed electron sources are concerned; however, the aim of this thesis will focus on single-shot measurement techniques whereby a sample is imaged by a single electron pulse. In particular, I present my theoretical and experimental work in the search for the ideal photocathode material, focusing on the photoemissive characterization of these materials via their bulk and surface properties. I also present a new photoelectron gun design implemented in the experimental photocathode characterization setup at UIC that improves and enhances data collection. Finally, I conclude with my investigations into the theory and simulation of radio frequency resonant cavities as objective lenses and aberration correctors for use in pulsed electron beam physics.