New dispersed fluorescence spectra of HCBr and DCBr

Dispersed fluorescence spectra following the excitation of several HCBr and DCBr A˜-X˜ vibronic bands were successfully obtained in a supersonic free jet expansion with an intensified charge-coupled device (ICCD) detector. These dispersed fluorescence spectra show signal-to-noise ratios of up to 100 and reveal the complete and detailed vibrational structure of the ground singlet state including the previously unreported C-H/D stretch vibrational mode. The emission bands to the background triplet state levels in DCBr were also observed for the first time and this confirms the singlet-triplet energy gap to be 2061 cm−1 (5.89 kcal/mol) in DCBr.