# Isomer-Dependent Fragmentation Dynamics of Inner-Shell Photoionized Difluoroiodobenzene

## TL;DR

This study investigates how two isomers of difluoroiodobenzene fragment after inner-shell photoionization, revealing different mechanisms and time scales through experimental momentum imaging and classical simulations.

## Contribution

It introduces a method to distinguish isomers based on momentum correlations and compares experimental results with simulations to elucidate fragmentation mechanisms.

## Key findings

- Different fragmentation mechanisms for the two isomers.
- Sequential fragmentation occurs on a time scale larger than rotational periods.
- Some breakup channels occur within a few hundred femtoseconds.

## Abstract

The fragmentation dynamics of 2,6- and 3,5-difluoroiodobenzene after iodine 4$d$ inner-shell photoionization with soft X-rays are studied using coincident electron and ion momentum imaging. By analyzing the momentum correlation between iodine and fluorine cations in three-fold ion coincidence events, we can distinguish the two isomers experimentally. Classical Coulomb explosion simulations are in overall agreement with the experimentally determined fragment ion kinetic energies and momentum correlations and point toward different fragmentation mechanisms and time scales. While most three-body fragmentation channels show clear evidence for sequential fragmentation on a time scale larger than the rotational period of the fragments, the breakup into iodine and fluorine cations and a third charged co-fragment appears to occur within a few hundred femtoseconds -- a time scale larger than the rotational period of the fragments, the breakup in other channels appears to occur within a few hundred femtoseconds.