Collisional removal of O2(b 1Σg+,v=1,2) by O2, N2, and CO2

A state-specific two-laser technique is used to investigate the collisional removal of O2 molecules in the b 1Σg+(v=1,2) levels, where we directly excite O2 and then probe the populations by resonance-enhanced multiphoton ionization. We find general agreement with earlier 300 K values for v=1 removal by O2, and show that v=2 removal is slower by a factor of 5.6±0.6 than v=1 removal. Only upper limits are obtained for N2 as a collider. For removal of v=1 in the atmosphere, N2 is unimportant compared to O2, but it might be competitive for v=2. For CO2 as a collider, addressing O2(b 1Σg+) removal in the atmospheres of Mars and Venus, the removal rate coefficients of the vibrationally-excited levels are similar to that for v=0. The significance of the large difference in the v=1 and v=2 rate coefficients for O2 collisions will be discussed as it relates to the modeling of recent earth nightglow observations.