Collisional removal of O2(b 1Σg+,υ=2,3)

The temperature dependence of the collisional removal of O-2 in the upsilon=3 level of the b (1)Sigma(g)(+) state by N-2, O-2, and CO2 was investigated at room temperature and below. Measurements on the upsilon=2 level with the colliders, O-2, N2O, Ar, and He are also reported. For upsilon=3 removal by O-2, the trend of sharply decreasing loss rate coefficients with increasing upsilon is seen to continue. For example, at 200 K the rate coefficient for collisional removal of O-2 from the upsilon=3 level by O-2 is some three orders of magnitude smaller than that for the upsilon=1 level. We argue that the mechanism of the deactivation is electronic-electronic (E-E) energy transfer. Observation of emission from a broad range of O-2(b (1)Sigma(g)(+)) vibrational levels in the terrestrial nightglow, recently discovered in astronomical sky spectra, show less than an order of magnitude difference in population between the more highly populated upsilon=3 level and the less populated upsilon=1 level. The implications of these two observations on the vibrational-level-specific atmospheric sources of vibrationally excited molecules in the b (1)Sigma(g)(+) electronic state are explored. (C) 2002 American Institute of Physics.