Femtosecond intramolecular rearrangement of the CH3NCS radical cation

TL;DR

This study uses femtosecond laser techniques and computational methods to investigate the ultrafast intramolecular rearrangement of the CH3NCS radical cation, revealing its timescale, vibrational coherence, and underlying driving forces.

Contribution

It provides the first detailed femtosecond-scale analysis of intramolecular rearrangement in CH3NCS radical cation using combined experimental and theoretical approaches.

Findings

Rearrangement occurs on a single picosecond timescale

Vibrational coherence is observed during rearrangement

Density functional and coupled-cluster calculations elucidate the driving forces

Abstract

Strong-field ionization, involving tunnel ionization and electron rescattering, enables femtosecond time-resolved dynamics measurements of chemical reactions involving radical cations. Here, we compare the formation of CH3S+ following the strong-field ionization of the isomers CH3SCN and CH3NCS. The former involves the release of neutral CN, while the latter involves an intramolecular rearrangement. We find the intramolecular rearrangement takes place on the single picosecond timescale and exhibits vibrational coherence. Density functional theory and coupled-cluster calculations on the neutral and singly ionized species help us determine the driving force responsible for intramolecular rearrangement in CH3NCS. Our findings illustrate the complexity that accompanies radical cation chemistry following electron ionization and demonstrate a useful tool for understanding the cation dynamics after ionization.