Graduate student Debadarshini Mishra, Department of Physics, University of Connecticut

Photo-Induced Ultrafast Dynamics in Molecules

Imaging electronic and molecular dynamics at ultrafast timescales is crucial for understanding the mechanisms of chemical reactions, which are of fundamental importance in fields ranging from materials science to biochemistry. Furthermore, gaining insights into these processes at the atomic and molecular levels can enable precise control over reaction dynamics, leading to significant technological advancements through the development of efficient catalysts, innovative materials, and targeted drugs. In this dissertation talk, I will present my work on imaging time-resolved dynamics in molecular systems, using various light sources and ultrafast spectroscopy techniques. First, I will discuss a method for the direct visualization of neutral fragments in roaming reactions, which involve an unconventional dissociation process, using coincident Coulomb explosion imaging. Next, I will explore ultrafast electron diffraction as a different yet complementary imaging technique to identify the competing non-radiative relaxation pathways for a UV-excited molecule. Finally, I will briefly discuss our recent work on relaxation and fragmentation dynamics in large molecules, particularly C60, and isomerization and excited-state dynamics in small molecules.