Dynamics of dissociation and photoionization by VUV and XUV photons revealed by ion fragment and photoelectron momentum imaging

We report recent progress on interrogating the highly-coupled electronic and nuclear dynamics in small molecules using vacuum- and extreme-ultraviolet pulses to excite, control and probe transient molecules on excited electronic states. A detailed understanding of photoionization mechanisms in these systems necessitates the ability to clearly distinguish metastable electronic states in the ionization continuum from direct photoionization [1]. Photoelectrons and fragment ions are analyzed by high-resolution cold target recoil ion momentum imaging (COLTRIMS), to identify and investigate these different pathways by the kinetic energy-resolved photoelectron and fragment angular distributions [2].

New results will be presented on the dynamics of dissociative photoionziation in diatomic molecules H₂, O₂ and N₂, using high harmonic generation. We will also discuss progress towards measurements of ultrafast time-resolved molecular-frame photoelectron angular distributions.