Super-resolution femtosecond electron diffraction reveals electronic and nuclear dynamics at conical intersections

TL;DR

This paper introduces a super-resolution ultrafast electron diffraction technique that visualizes nuclear and electronic motions at conical intersections with sub-angstrom precision, revealing ultrafast molecular dynamics.

Contribution

It combines mega-electron-volt ultrafast electron diffraction with a super-resolution algorithm to surpass the diffraction limit in real-space imaging of molecular conical intersections.

Findings

Resolved nuclear and electronic motions at conical intersections.

Measured C-C bond length differences less than 0.4 Å.

Observed a 30-fs nuclear wave packet traversal time.

Abstract

Conical intersections play a pivotal role in excited-state quantum dynamics. Capturing transient molecular structures near conical intersections remains challenging due to the rapid timescales and subtle structural changes involved. We overcome this by combining the enhanced temporal resolution of mega-electron-volt ultrafast electron diffraction with a super-resolution real-space inversion algorithm, enabling visualization of nuclear and electronic motions at conical intersections with sub-angstrom resolution, surpassing the diffraction limit. We apply this technique to the textbook example of the ring-opening reaction of 1,3-cyclohexadiene, which proceeds through two conical intersections within 100 femtoseconds. The super-resolved transient structures near conical intersections reveal a C-C bond length difference of less than 0.4 angstrom and an approximately 30-femtosecond traversal time of the nuclear wave packet between them. These findings establish super-resolution ultrafast scattering as a transformative tool for uncovering quantum dynamics in molecules and open new avenues for studying light-matter interactions at the most fundamental level.