Dichloroethene L-Edge Photofragmentation Dynamics and Bond-Length Dependent Core-Hole Localization

The interaction of light and matter is a fundamental interaction in nature. In general, a detailed understanding of correlated dynamics involved in photoionization and photofragmentation is an opportunity for the advancement of both experimental and theoretical physics. The UNR COLd Target Recoil Ion Momentum Spectroscopy (COLTRIMS) apparatus has been developed to act as an experimental technique to investigate many-particle dynamics associated with photoionization at a range of user facilities. The possibility to determine soft X-ray site-specific ionization for identical mass atoms within a molecule is an open question in quantum physics. This dissertation details a study of two isomers, 1,1 and 1,2-trans dichloroethene, designed to investigate the phenomena of site-specific localized core-hole ionization. This experiment used photoionization of chlorine atoms within dichloroethene performed at the Advanced Light Source beam-line 9.0.1 at Lawrence Berkeley National Lab in November 2019. In the 1,1 dichloroethene data set, state and bond-length dependent core-hole localization was shown following chlorine L-edge ionization

Step-by-step state-selective tracking of fragmentation dynamics of water dications by momentum imaging.

The double photoionization of a molecule by one photon ejects two electrons and typically creates an unstable dication. Observing the subsequent fragmentation products in coincidence can reveal a surprisingly detailed picture of the dynamics. Determining the time evolution and quantum mechanical states involved leads to deeper understanding of molecular dynamics. Here in a combined experimental and theoretical study, we unambiguously separate the sequential breakup via D+ + OD+ intermediates, from other processes leading to the same D+ + D+ + O final products of double ionization of water by a single photon. Moreover, we experimentally identify, separate, and follow step by step, two pathways involving the b 1Σ+ and a 1Δ electronic states of the intermediate OD+ ion. Our classical trajectory calculations on the relevant potential energy surfaces reproduce well the measured data and, combined with the experiment, enable the determination of the internal energy and angular momentum distribution of the OD+ intermediate