Photodissociation of bromobenzene at 267 and 234 nm: experimental and theoretical investigation of the photodissociation mechanism

The photodissociation of bromobenzene at 267 and 234 nm was investigated with time-of-flight (TOF) mass spectrometry. After the photodissociation, smaller branching ratios Br*(2P1/2)/Br (2P3/2) of bromobenzene, compared to that of 1-bromoheptane, were observed by subsequent (2 + 1) resonance-enhanced multiphoton ionization (REMPI) processes. The reduction of the branching ratio can be explained by a different photodissociation mechanism of aryl halides from that of alkyl halides. Also, the branching ratio of bromobenzene decreases with the reducing of the laser wavelength. Based on this finding and our ab initio calculations, a possible photodissociation mechanism of bromobenzene was proposed.