Identification of the roaming mechanism and the formation of H3+ in core ionised cyclopropane

Abstract

Spectroscopic validation of the roaming process in molecular dissociation was first reported for formaldehyde, but today roaming is acknowledged to be a nearly ubiquitous dissociation pathway. The process has been described as a frustrated dissociation process, and as such, direct detection of the roaming process is challenging. In the present study the cyclopropane dication is the starting point for a roaming process that results in the production of H₃⁺. In our experiment, we measure the complete momenta of all charged fragments and unravel the kinematics for relevant fragmentation processes. We present a comprehensive study of the process comparing alternative pathways for dissociation and their kinematics in association to the roaming process. In this study, inner-shell electron ionisation leads to dication states, these final electronic states are fundamentally identical to ones reached via direct double ionisation.