Photoelectron Spectroscopy Using a Synthetically Chiral Laser Pulse

Title: Photoelectron Spectroscopy Using a Synthetically Chiral Laser Pulse
Authors: Dube, Zack
Date: 2023-05-25
Abstract: Chiral molecules are composed of the same constituent atoms, but are inherently different due to being mirror images of each other. The physical properties of such molecules are nearly identical, but the biochemical interactions can differ wildly, which has extreme implications in the pharmaceutical industry. It is for this reason that it is important to be able to characterize and study individual enantiomers, and develop physical methods to do so. Optical techniques have evolved over the past two decades of scientific work which have been shown to be able to distinguish one enantiomer from another. These techniques tend to involve the use of circularly polarized light to induce a forward/backward asymmetry along the axis of light's propagation. The resulting sensitivity difference between enantiomers is typically on the order of a few percent. Recently, a novel optical pulse scheme has been developed whose electric field is fully three-dimensional and inherently chiral. This field was computationally used to demonstrate that the signal difference between enantiomers can reach upwards of 100\% sensitivity through the generation of high harmonics. Presented in this thesis are the results of an experimental measurement performed using just such a novel pulse scheme. A cold target recoil ion momentum spectroscopy machine is used to detect the photoelectron spectra from the ionization of each enantiomer of propylene oxide. A comprehensive discussion on the practical realization of the novel pulse scheme is presented, and the circular dichroism due to the novel field is shown. Also discussed are fragmentation of propylene oxide, three dimensional chiral signals found in the data, and a new measure to define the magnitude of chirality in a photoelectron distribution. Finally, measurements pertaining to the ionic yield of each enantiomer under varying handedness of light are shown. These results are the first experimental realization of optical measurements using synthetically designed chirality.
CollectionThèses, 2011 - // Theses, 2011 -