A3Pi1u<--X1Sigmag+ laser photoacoustic spectroscopy of Br2 vapor in the extreme red wavelength region 665-720 nm

The A3Pi1u<--X1Sigmag+ photoacoustic spectrum of Br2 vapor has been studied and vibronic analysis performed using earlier data available for this system of bands from optical spectroscopy in the region 665-720 nm. The vibronic levels involved in these transitions are 4< or =v'< or =21 and 1< or =v'< or =4. The relative photoacoustic intensities of the vibronic bands have been used in estimating the non-radiative relaxation rate from vibrational levels of A3Pi(1u) state. The non-radiative relaxation is found to be a nonlinear function of the upper state vibrational quantum number. The radiative rate constants for the A3Pi(1u) state vibrational levels have been compared with the corresponding non-radiative constants obtained from present work. Non-radiative decay rate constants for the vibrational levels of A3Pi(1u) state have been experimentally determined for the first time from photoacoustic spectrum of Br2 vapor in the extreme red region.