Time-Resolved Coulomb Explosion Imaging Unveils Ultrafast Ring Opening of Furan

TL;DR

This study uses time-resolved Coulomb explosion imaging combined with simulations to directly visualize and confirm an ultrafast ring-opening reaction in gas-phase furan occurring within 100 femtoseconds.

Contribution

It demonstrates the first direct imaging of ultrafast ring-opening in furan, resolving conflicting previous reports through combined experimental and theoretical approaches.

Findings

Ultrafast ring-opening occurs within 100 fs after UV excitation.

Experimental data combined with simulations confirm the ring-opening pathway.

Contradictory previous predictions are clarified by this study.

Abstract

Following the changes in molecular structure throughout the entirety of a chemical reaction with atomic resolution is a long-term goal in femtochemistry. Although the development of a plethora of ultrafast technique has enabled detailed investigations of the electronic and nuclear dynamics on femtosecond time scales, direct and unambiguous imaging of the nuclear motion during a reaction is still a major challenge. Here, we apply time-resolved Coulomb explosion imaging with femtosecond near-infrared pulses to visualize the ultraviolet-induced ultrafast molecular dynamics of gas-phase furan. Widely contradicting predictions and observations for this molecule have been reported in the literature. By combining the experimental Coulomb explosion imaging data with ab initio molecular dynamics and Coulomb explosion simulations, we reveal the presence of a strong ultrafast ring-opening pathway upon excitation at 198 nm that occurs within 100 fs.