State-specific rate constants for the relaxation of O-2(X(3)Sigma(-)(g), v=8-11) in collisions with O-2, N-2, NO2, CO2, N2O, CH4 and He

Rate constants have been measured at 295 K for the state-specific vibrational relaxation of O-2(8 less than or equal to upsilon less than or equal to 11) by several gases, M = NO2, O-2, CO2, N2O, CH4 and He. Upper limits are reported for the rate constants for relaxation by N-2. Vibrationally excited O-2 was formed in levels up to upsilon = 11 by the reaction of O(P-3) atoms with NO2. The O(P-3) atoms were created by partial photolysis of NO2 at 355 nm using. frequency-tripled Nd:YAG laser, and the kinetics of O-2 in individual upsilon levels observed by laser-induced fluorescence in the (0, upsilon) bands of the B (3) Sigma(u)(-)-X(3) Sigma(g)(-) system. Except with He as collision partner, it appears that relaxation occurs by single quantum, intermolecular, vibration-vibration (V-V) energy exchange. Comparison of the rate constants for relaxation by different collision partners demonstrates again the importance of near-resonance and long-range forces in facilitating V-V exchange, with IR active modes accepting vibrational quanta more readily than IR inactive modes. The results are compared with those obtained previously for higher vibrational levels of O-2, with estimates of the relaxation rates estimated according to a version of Sharma-Brau theory, and the implications of the results for atmospheric chemistry are discussed briefly.