Abstract:
Here I present studies for the manipulation of free electrons using materialholograms and the application of holographically structured electrons in
interferometry. The research in this dissertation can be divided into two main
sections. First, is the design and nanofabrication of off-axis material holograms
for free electrons that can be used to arbitrarily shape the amplitude and phase
of the electron wavefront. Focused ion beam gas-assisted etching is presented
as a method to reliably achieve the fabrication resolution required to produce
the intended grating groove profiles to optimize diffraction efficiency and meet
the precise hologram depth profiles required to impart a desired structured
wavefront. An analytical method for finding hologram groove profiles is also
outlined and experimental tests are performed to verify its accuracy. In the second
portion, binary straight diffraction gratings are placed in a transmission electron
microscope to create a scanning two-grating Mach-Zehnder interferometer. The
sensitivity of the relative phases in the interferometer output are shown through
the relative alignment of the gratings, as well as by introducing external phase
shifts from static potentials to the path separated probes. The interferometer's
capability to achieve phase sensitive nanoscale imaging is also demonstrated.
Finally, the interferometer is used to measure interference between a coherent
superposition of electrons inelastically scattered from the dipole plasmon of a gold
nanoparticle.
This dissertation contains previously published and unpublished material.