Ultrafast molecular dynamics of dissociative ionization in OCS probed by soft X-ray synchrotron radiation

TL;DR

This study investigates ultrafast dissociative ionization in OCS molecules using soft X-ray synchrotron radiation, revealing new insights into ionization dynamics, timescale effects, and breakup pathways through advanced detection and analysis techniques.

Contribution

It provides novel observations of ionization processes and breakup mechanisms in OCS, including timescale effects and out-of-equilibrium nuclear configurations, using Dalitz plots and variable X-ray energies.

Findings

Kinetic energy release limited by photon energy.

Evidence of timescale effects between direct and Auger ionization.

Breakup involving O$^{2+}$ ion requires out-of-equilibrium nuclear arrangement.

Abstract

Soft X-rays (90-173 eV) from the 3rd generation Canadian Light Source have been used in conjunction with a multi coincidence time and position sensitive detection apparatus to observe the dissociative ionization of OCS. By varying the X-ray energy we can compare dynamics from direct and Auger ionization processes, and access ionization channels which result in two or three body breakup, from 2+ to 4+ ionization states. We make several new observations for the 3+ state such as kinetic energy release limited by photon energy, and using Dalitz plots we can see evidence of timescale effects between the direct and Auger ionization process for the first time. Finally, using Dalitz plots for OCS$^{4+}$ we observe for the first time that breakup involving an O$^{2+}$ ion can only proceed from out of equilibrium nuclear arrangement for S(2p) Auger ionization.