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.
@article{arxiv.1904.01515,
title = {Diffractive imaging of dissociation and ground state dynamics in a complex molecule},
author = {Kyle Wilkin and Robert Parrish and Jie Yang and Thomas J. A. Wolf and Pedro Nunes and Markus Guehr and Renkai Li and Xiaozhe Shen and Qiang Zheng and Xijie Wang and Todd J. Martinez and Martin Centurion},
journal= {arXiv preprint arXiv:1904.01515},
year = {2019}
}