Spectroscopic Signature of Chemical Bond Dissociation Revealed by Calculated Core-Electron Spectra

TL;DR

This paper demonstrates how ultrafast soft x-ray spectroscopy can reveal detailed real-time signatures of chemical bond dissociation, specifically in methyl iodide, by simulating time-dependent electron spectra.

Contribution

It introduces a method to simulate and interpret time-resolved core-electron spectra for tracking ultrafast bond breaking in molecules.

Findings

Distinct spectral signatures correlate with C-I bond dissociation.

Simulated spectra reveal charge rearrangement during bond breaking.

Method enables detailed mapping of ultrafast photodissociation dynamics.

Abstract

The advent of ultrashort soft x-ray pulse sources permits the use of established gas phase spectroscopy methods to investigate ultrafast photochemistry in isolated molecules with element and site specificity. In the present study, we simulate excited state wavepacket dynamics of a prototypical process, the ultrafast photodissociation of methyl iodide. Based on the simulation, we calculate time-dependent excited state carbon edge photoelectron and Auger electron spectra. We observe distinct signatures in both types of spectra and show their direct connection to C-I bond dissociation and charge rearrangement processes in the molecule. We demonstrate at the CH$_3$I molecule that the observed signatures allow us to map the time-dependent dynamics of ultrafast photo-induced bond breaking with unprecedented details.