Jahn-Teller Distortion and Dissociation of CCl$_4^+$ by Transient X-ray Spectroscopy Simultaneously at the Carbon K- and Chlorine L-Edge

TL;DR

This study uses transient X-ray spectroscopy and theoretical calculations to observe the ultrafast Jahn-Teller distortion and dissociation process of CCl4+ ions, revealing new intermediate species and dynamics.

Contribution

It provides the first direct observation of Jahn-Teller distortion and subsequent dissociation pathways of CCl4+ using simultaneous K- and L-edge X-ray spectroscopy combined with theoretical modeling.

Findings

Jahn-Teller distortion occurs within 6±2 fs after ionization.

Formation of a noncovalently bound CCl3+--Cl complex within 90±10 fs.

Complete dissociation into free CCl3+ and Cl observed after 800 fs.

Abstract

X-ray Transient Absorption Spectroscopy (XTAS) and theoretical calculations are used to study CCl$_4^+$ prepared by 800 nm strong-field ionization. XTAS simultaneously probes atoms at the carbon K-edge (280-300 eV) and chlorine L-edge (195-220 eV). Comparison of experiment to X-ray spectra computed by orbital-optimized density functional theory (OO-DFT) indicates that after ionization, CCl$_4^+$ undergoes symmetry breaking driven by Jahn-Teller distortion away from the initial tetrahedral structure (T$_d$) in 6$\pm$2 fs. The resultant symmetry-broken covalently bonded form subsequently separates to a noncovalently bound complex between CCl$_3^+$ and Cl over 90$\pm$10 fs, which is again predicted by theory. Finally, after more than 800 fs, L-edge signals for atomic Cl are observed, indicating dissociation to free CCl$_3^+$ and Cl. The results for Jahn-Teller distortion to the symmetry-broken form of CCl$_4^+$ and formation of the Cl -- CCl$_3^+$ complex characterize previously unobserved new species along the route to dissociation.