UV-induced Ring-opening dynamics investigated using Coulomb Explosion Imaging

The UV-induced ring-opening reaction is a widely studied process of significant importance in molecular dynamics. Thiophenone (C4H4OS) has been used as a model ring molecule in these investigations [1]. However, techniques such as time-resolved photoelectron spectroscopy and ultrafast electron diffraction have limitations in providing direct molecular structural information and sub-100 fs temporal resolution, respectively. In this work, we present the results of experiments that employ Coulomb Explosion Imaging with intense X-rays or near-infrared laser pulses . We use a UV pulse at 266 nm to excite the molecule and a high-intensity X-ray or near-infrared (NIR) laser pulse to probe the evolving molecular structure at different time delays. By detecting ionic fragments in coincidence, we are able to capture the dynamics of the ring-opening reaction with high temporal resolution. The experimental results are compared to Coulomb explosion simulations to assist the interpretation.

[1] S. Pathak et al. Nature Chemistry 12, 795–800 (2020)