Double ionisation of ICN and BrCN studied by a new photoelectron–photoion coincidence technique

A double time-of-flight technique is described, whereby any number of electrons and ions produced by photoionisation can be detected in coincidence, with energy analysis for the electrons and mass analysis for the ions. Branching ratios, kinetic energy releases and mechanisms in doubly charged ion decays can be measured with selection of the initial double ionisation energy. The new technique, together with spectroscopy by the recently established time-of-flight photoelectron–photoelectron coincidence (TOF-PEPECO) method, is used to study the spectra and dissociation dynamics of ICN⁺⁺ and BrCN⁺⁺.