Quantum resolved rotational energy transfer in the B 3Π(0+u) state of Br2

Abstract

Steady-state spectrally resolved laser-induced fluorescence techniques have been used to study rotational energy transfer within the B 3Π(0u+) state of molecular bromine. Rate coefficients for electronic quenching and state-to-state rotational energy transfer within vibrational state v′=11 were determined for Br2, He, Ar, and Xe collision partners. The individual, state selective rotational transfer rate coefficients were an order of magnitude slower than electronic quenching rates. Electronic quenching is attributed to both collisional predissociation and energy transfer followed by rapid spontaneous predissociation. For Br2(B, v′=11, J′=35) collisions with helium, population in the states J′=19–47 were observed and the resulting state-to-state rotational transfer rate coefficients ranged from 6.2×10−11 to 6.5×10−12 cm3/molecule s. Both exponential energy gap and statistical power gap laws for the scaling of rotational energy transfer rate coefficients with rotational energy are compared to the observed data.