# Isomer-selective dissociation dynamics of 1,2-dibromoethene ionised by femtosecond-laser radiation

## TL;DR

This study explores how different isomers of 1,2-dibromoethene break apart when exposed to ultrafast laser pulses, revealing isomer-specific chemical behaviors.

## Contribution

The study reveals isomer-specific dissociation dynamics under femtosecond laser irradiation, highlighting differences in photofragmentation pathways.

## Key findings

- Isomer-specific photofragmentation dynamics are observed for Br+ and C2H2Br+ channels.
- C2H2+ photofragment formation shows no significant isomer dependence.
- Isomer effects in photochemistry are emphasized even in small polyatomic molecules.

## Abstract

We study the isomer-specific photoionisation and photofragmentation of 1,2-dibromoethene (DBE) under strong-field fs-laser irradiation in the gas phase complementing previous studies utilising ns- and ps-laser excitation. Our findings are compatible with a dissociative multiphoton-ionisation mechanism producing a variety of ionic photofragments. Using both Stark deflection and chemical separation of the two isomers, pronounced isomer-specific photofragmentation dynamics could be observed for different product channels. While for Br+ formation, the isomer specificity appears to originate from different photoexcitation efficiencies, for the C2H2Br+ channel it is more likely caused by differences in the coupling to the exit channel. By contrast, the formation of the C2H2+ photofragment does not seem to exhibit a pronounced isomeric dependence under the present conditions. The present work underlines the importance of isomeric effects in photochemistry even in small polyatomics like the present system as well as their pronounced dependence on the photoexcitation conditions.

We study the isomer-specific photoionisation and photofragmentation of 1,2-dibromoethene (DBE) under strong-field fs-laser irradiation in the gas phase complementing previous studies utilising ns- and ps-laser excitation.