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Tracing the 267 nm-Induced Radical Formation in Dimethyl Disulfide Using Time-Resolved X‑ray Absorption Spectroscopy
Journal article   Peer reviewed

Tracing the 267 nm-Induced Radical Formation in Dimethyl Disulfide Using Time-Resolved X‑ray Absorption Spectroscopy

Kirsten Schnorr, Aditi Bhattacherjee, Katherine J Oosterbaan, Mickaël G Delcey, Zheyue Yang, Tian Xue, Andrew R Attar, Adam S Chatterley, Martin Head-Gordon, Stephen R Leone, …
The journal of physical chemistry letters, Vol.10(6), pp.1382-1387
03/21/2019
DOI: 10.1021/acs.jpclett.9b00159
PMID: 30835480
url
https://escholarship.org/uc/item/6pb2v9qdView
Open Access

Abstract

Disulfide bonds are pivotal for the structure, function, and stability of proteins, and understanding ultraviolet (UV)-induced S–S bond cleavage is highly relevant for elucidating the fundamental mechanisms underlying protein photochemistry. Here, the near-UV photodecomposition mechanisms in gas-phase dimethyl disulfide, a prototype system with a S–S bond, are probed by ultrafast transient X-ray absorption spectroscopy. The evolving electronic structure during and after the dissociation is simultaneously monitored at the sulfur L1,2,3-edges and the carbon K-edge with 100 fs (FWHM) temporal resolution using the broadband soft X-ray spectrum from a femtosecond high-order harmonics light source. Dissociation products are identified with the help of ADC and RASPT2 electronic-structure calculations. Rapid dissociation into two CH3S radicals within 120 ± 30 fs is identified as the major relaxation pathway after excitation with 267 nm radiation. Additionally, a 30 ± 10% contribution from asymmetric CH3S2 + CH3 dissociation is indicated by the appearance of CH3 radicals, which is, however, at least partly the result of multiphoton excitation.

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