Delayed Dissociation\nand Transient Isomerization during\nthe Ultrafast Photodissociation of the Tribromomethane Cation

We present a time-resolved measurement of the photodissociation\nand photoisomerization dynamics of bromoform (CHBr<sub>3</sub>) in\nthe mono- and di-cationic states produced by near-infrared (NIR) strong-field\nionization. The dissociation process is probed by NIR-induced Coulomb\nexplosion imaging. We find that for dissociation channels involving\nproduction of HBr and Br<sub>2</sub> fragments, which require the\nformation of new bonds, the dissociation appears to be delayed with\nrespect to the primary C–Br bond dissociation channel. <i>Ab initio</i> molecular dynamics simulations support the observed\ndelay. Moreover, the simulations suggest that reaction pathways involving\ntransient isomerization via H- and Br-migration in the CHBr<sub>3</sub> monocation are responsible for the formation of the HBr and Br<sub>2</sub> fragments.