KINETICS FOR THE QUENCHING AND RELAXATION OF BORON-OXIDE

Laser induced fluorescence studies are described in this paper for the kinetics of BO(A 2PI) quenching, vibrational and rotational relaxation, and for the radiative lifetime of the A 2PI state. Measured electronic quenching rates with several gases are presented. The rates are reasonably slow with He, Ar, N2, N2O, and CF4, as the collisional partners. The gases O2, F2, NO, and NO2 show a very fast quenching of the A 2PI state, probably as a consequence of chemical reaction with BO along with collisional energy transfer. Vibrational relaxation is generally slow compared to quenching except with CF4 where the collisional partner has a vibrational structure in near resonance with that of BO(A 2PI). Rotational relaxation in BO(A) by He, NO, O2, CF4, and SF6 was found to be fast, as would be expected in a molecule with closely spaced energy levels. The effects on the BO spectra of vibrational transfer with CF4 are shown. Quenching rates for BO(A 2PI) v = 0 and 2 measured over a series of helium pressure extrapolate to values of 1.75 and 1.37 mus for the radiative lifetimes of the v' = 0 and 2 levels.