State-specific rate constants for the relaxation of O2(X 3∑g−) from vibrational levels v=8 to 11 by collisions with NO2 and O2

Rate constants are reported for the state-specific vibrational relaxation of O2 (8⩽v⩽11) by NO2 and O2 at 295 K. O2 is formed in vibrational levels up to v=11 by the reaction of O(3P) atoms with NO2. The oxygen atoms were created by partial photolysis of NO2 at 355 nm using a frequency-tripled Nd:YAG laser, and the kinetics of O2 in particular v levels observed by laser-induced fluorescence in the (0, v) bands of the B 3∑u−-X3∑g− system. The rate constants for relaxation of O2 by NO2 in units of 10−13 cm3 molecule−1 s−1, are 5.5±1.2, 6.8±1.1, 9.3± 1.2, 7.0±0.8 for v=8, 9, 10, 11, respectively, and by O2, in units of 10−14 cm3molecule−1 s−1, are 8.5±1.7, 10.8±1.7, 8.2±1.4, 7.5±0.3 for v=8, 9, 10, 11, respectively. The results are compared with those obtained previously for higher vibrational levels of O2, and their implications for atmospheric chemistry are discussed briefly.