Photodissociation studies of CBr(4) (+) and CBr(3) (+) at 267 nm using ion velocity imaging

Time-of-flight (TOF) mass spectroscopy and ion velocity imaging were employed to study the formation and photodissociation of CBr(4) (+) and CBr(3) (+) ions that were observed in the TOF spectrum when a CBr(4) beam was irradiated with 118 nm and 355 nm lasers. Energy dependence measurements show that both CBr(4) (+) and CBr(3) (+) ions depend on the fourth power of the 355 nm laser energy, which indicates that direct ionization and dissociative ionization of CBr(4) have low probabilities from the state initially excited at 118 nm. This is likely due to the large geometry change in the CBr(4) (+) ion. Two ionic fragments Br(+) and CBr(2) (+) were observed from the dissociation of CBr(4) (+) and CBr(3) (+) ions when another laser at 267 nm was introduced to the interaction region at a delayed time. The possible dissociation pathways and the angular and translational distributions are discussed in the paper.