Study on the photodissociation mechanisms of m-bromotoluene at 234 and 267 nm using velocity ion imaging

The Photodissociation dynamics of m-bromotoluene with excitation laser wavelength at 234 and 267 nm has been investigated by velocity ion imaging coupled with resonance-enhanced multiphoton ionization. The speed and angular distributions of Br and Br∗ fragments are determined. Promptly direct dissociation via repulsive a n → σ∗ transition is displayed at 234 nm. At 267 nm, fast pre-dissociation processes via a π → π∗ transition to a singlet state followed by an intersystem cross between the singlet state and a repulsive triplet state is found, and multiphoton dissociative ionization process is also suggested.