Energy transfer dynamics in the A(0 u+) state of Bi 2

Abstract

Laser induced fluorescence, pulsed and CW, techniques have been used to study energy transfer within the A(0 u + ) state of Bi 2 . In particular, electronic quenching in the vibrational levels near predissociation, v' equals 18-25, have been examined for rare gas and nitrogen collision partners. The quenching from non-predissociated levels is independent of vibrational state and are rather rapid, 2.3 - 8.5 X 10 -11 cm 3 molecule-s for v' equals 22. The quenching from the first significantly predissociated level, v' equals 23, is even faster with rate coefficients ranging from 7.4 - 15.7 X 10 -11 cm 3 molecule-s. Heterogeneous predissociation is very rapid for 21 -1 . Vibrational-to-translational energy transfer probabilities for the lowest vibrational levels, v' equals 0-4, range from 0.75 - 1.75 percent per collision, considerably lower than would be anticipated for these highly non-adiabatic collisions. Spectrally resolved emissions from collisionally populated rotational levels of Bi2(A,v' equals 1) were observed for helium, neon and argon collision partners after laser excitation of the high rotational levels J' equals 171, 201, and 231. Total rotational removal rates from the initially prepared state range from 2.8 - 8.9 X 10 -10 cm 3 molecule-s. Collisional population of rotational states with (Delta) J <EQ 56 was observed at pressures of 0.09 - 1.4 torr. The state-to-state rates are adequately modeled by the energy based statistical power gap law.