Systematical Study on Photodissociation Dynamics of BrCN from 225 nm to 260 nm

The photodissociation dynamics of Br - C bond cleavage for BrCN in the wavelength region from 225 nm to 260 nm has been studied by our homebuilt time-slice velocity-map imaging setup. The images for both of the ground state Br( ^2 \rmP_3/2 ) and spin-orbit excited Br ^* ( ^2 \rmP_1/2 ) channels are obtained at several photodissociation wavelengths. From the analysis of the translational energy release spectra, the detailed vibrational and rotational distributions of CN products have been measured for both of the Br and Br ^* channels. It is found that the internal excitation of the CN products for the Br ^* channel is colder than that for the Br channel. The most populated vibrational levels of the CN products are v =0 and 1 for the Br and Br ^* channels, respectively. For the Br channel, the photodissociation dynamics at longer wavelengths are found to be different from those at shorter wavelengths, as revealed by their dramatically different vibrational and rotational excitations of the CN products.