Coulomb explosion of CD3I induced by single photon deep inner-shell ionisation

TL;DR

This study investigates the Coulomb explosion of fully deuterated methyl iodide (CD3I) caused by deep inner-shell ionisation with hard x-rays, combining experimental measurements with numerical simulations to understand charge state distributions.

Contribution

It introduces a combined experimental and numerical approach to analyze Coulomb explosion dynamics induced by inner-shell ionisation in CD3I, highlighting the need to include nuclear motion for high charge states.

Findings

Charge states up to 16+ observed after ionisation.

Good agreement between simulations and experiments for medium charge states.

Deviations at high charge states indicate the importance of nuclear motion.

Abstract

L-shell ionisation and subsequent Coulomb explosion of fully deuterated methyl iodide, CD$_3$I, irradiated with hard x-rays has been examined by a time-of-flight multi-ion coincidence technique. The core vacancies relax efficiently by Auger cascades, leading to charge states up to 16+. The dynamics of the Coulomb explosion process are investigated by calculating the ions' flight times numerically based on a geometric model of the experimental apparatus, for comparison with the experimental data. A parametric model of the explosion, previously introduced for multi-photon induced Coulomb explosion, is applied in numerical simulations, giving good agreement with the experimental results for medium charge states. Deviations for higher charges suggest the need to include nuclear motion in a putatively more complete model. Detection efficiency corrections from the simulations are used to determine the true distributions of molecular charge state produced by initial L1, L2 and L3 ionisation.