Jahn-Teller distortion and dissociation of CCl₄⁺ by transient X-ray spectroscopy simultaneously at the carbon K- and chlorine L-edge

Abstract

X-ray Transient Absorption Spectroscopy (XTAS) and theoretical calculations are used to study CCl₄ ⁺ 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, CCl₄ ⁺ undergoes symmetry breaking driven by Jahn-Teller distortion away from the initial tetrahedral structure (T_d) in 6 ± 2 fs. The resultant symmetry-broken covalently bonded form subsequently separates to a noncovalently bound complex between CCl₃ ⁺ and Cl over 90 ± 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 CCl₃ ⁺ and Cl. The results for Jahn-Teller distortion to the symmetry-broken form of CCl₄ ⁺ and formation of the Cl-CCl⁺ ₃ complex characterize previously unobserved new species along the route to dissociation.