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

Andrew D Ross; Diptarka Hait; Valeriu Scutelnic; Eric A Haugen; Enrico Ridente; Mikias B Balkew; Daniel M Neumark; Martin Head-Gordon; Stephen R Leone

doi:10.1039/d2sc02402k

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

Chem Sci. 2022 Jul 19;13(32):9310-9320. doi: 10.1039/d2sc02402k. eCollection 2022 Aug 17.

Authors

Andrew D Ross^{1

2}, Diptarka Hait^{1

2}, Valeriu Scutelnic^{1

2}, Eric A Haugen^{1

2}, Enrico Ridente¹, Mikias B Balkew^{3

1}, Daniel M Neumark^{1

2}, Martin Head-Gordon^{1

2}, Stephen R Leone^{1

2

4}

Affiliations

¹ Department of Chemistry, University of California Berkeley 94720 CA USA [email protected].
² Chemical Sciences Division, Lawrence Berkeley National Laboratory Berkeley 94720 CA USA.
³ School of Physics, Georgia Institute of Technology Atlanta 30332 GA USA.
⁴ Department of Physics, University of California Berkeley 94720 CA USA.

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.