Ultrafast molecular dynamics in ionized 1- and 2-propanol: from simple fragmentation to complex isomerization and roaming mechanisms

We will present time-resolved ultrafast nuclear dynamics in ionized 1- and 2-propanol, observed using a combination of pump-probe spectroscopy and coincident Coulomb explosion imaging. Using the experimental data along with quantum chemistry calculations, we identify the two- and three-body breakup channels for both isomers. These isomers exhibit a wide variety of dynamics ranging from direct C-C bond fragmentation to hydrogen migration which are supported by state-of-the-art molecular dynamics simulations. Additionally, the direct fragmentation channel in 2-propanol shows evidence of methyl roaming which manifests as a unique distribution in the kinetic energy release spectrum. We find that the electronic distribution of the roaming methyl fragment is potentially responsible for the enhanced ionization we also observe in this channel. We conclude by comparing the dynamics of 1- and 2-propanol with similar studies done on ethanol and acetonitrile, which establishes a correlation between the carbon chain length and probability of hydrogen migration.