Ultrafast study of the photodissociation of bromoiodomethane in acetonitrile upon 266 nm excitation

We studied the A-band photodissociation of bromoiodomethane, CH2BrI, in acetonitrile solution at room temperature by femtosecond pump-probe spectroscopy, Initiated by the 266 nm light, this reaction leads to the CH2Br-I isomer, most likely produced via in-cage recombination of the CH,Br and I photofragments. The isomer is formed vibrationally excited with a time constant of similar to7.5 ps and the hottest isomer molecules are observed as early as I ps after the UV excitation, Vibrational relaxation of the isomer molecules takes place on two distinct time scales of a few and similar to40 ps. The ground-state lifetime of the isomer is about 2.5 ns.