# Diffractive imaging of dissociation and ground state dynamics in a complex molecule

## TL;DR

This study combines ultrafast electron diffraction experiments and theoretical simulations to observe real-time molecular dissociation and ground state dynamics in photoexcited C2F4I2 molecules, revealing sub-angstrom nuclear motions and rapid stabilization.

## Contribution

It provides the first combined experimental and theoretical analysis of ultrafast dissociation and vibrational dynamics in a complex molecule with sub-angstrom resolution.

## Key findings

- Observation of iodine atom dissociation dynamics
- Detection of coherent vibrations in the ground state
- Radical stabilization within 200 femtoseconds

## Abstract

We have investigated the structural dynamics in photoexcited 1,2-diiodotetrafluoroethane molecules (C2F4I2) in the gas phase experimentally using ultrafast electron diffraction and theoretically using FOMO-CASCI excited state dynamics simulations. The molecules are excited by an ultra-violet femtosecond laser pulse to a state characterized by a transition from the iodine 5p orbital to a mixed 5p|| hole and CF2 antibonding orbital, which results in the cleavage of one of the carbon-iodine bonds. We have observed, with sub-Angstrom resolution, the motion of the nuclear wavepacket of the dissociating iodine atom followed by coherent vibrations in the electronic ground state of the C2F4I radical. The radical reaches a stable classical (non-bridged) structure in less than 200 fs.

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Source: https://tomesphere.com/paper/1904.01515