Photophysics of indole upon x-ray absorption

TL;DR

This study investigates the photophysics of indole after x-ray absorption, revealing fragmentation pathways, electron spectra linked to structural dynamics, and evidence of photoelectron-impact self-ionization.

Contribution

It provides new insights into indole's inner-shell ionization and fragmentation dynamics using coincidence measurements at high photon energy.

Findings

Fragmentation pathways depend on molecular structure.

Electron spectra vary with fragmentation channels.

Evidence of photoelectron-impact self-ionization was observed.

Abstract

A photofragmentation study of gas-phase indole (C$_8$H$_7$N) upon single-photon ionization at a photon energy of 420 eV is presented. Indole was primarily inner-shell ionized at its nitrogen and carbon $1s$ orbitals. Electrons and ions were measured in coincidence by means of velocity map imaging. The angular relationship between ionic fragments is discussed along with the possibility to use the angle-resolved coincidence detection to perform experiments on molecules that are strongly oriented in their recoil-frame. The coincident measurement of electrons and ions revealed fragmentation-pathway-dependent electron spectra, linking the structural fragmentation dynamics to different electronic excitations. Evidence for photoelectron-impact self-ionization was observed.