Vibrational-level-dependent yields of O2(b 1Σg+, v=0) following collisional removal of O2(A 3Σu+, v)

The vibrational level dependence of the branching ratio for the production of O2(b 1Σg+, v=0) from the collisional deactivation of O2(A 3Σu+) with ground-state O2 is studied. Using the ultraviolet output from a frequency-doubled tunable dye laser, we excite O2 molecules to a specific vibrational level (5≤v≤9) in the A 3Σu+ state and monitor the b 1Σg+–X 3Σg− fluorescence near 762 nm. The relative signals following excitation to different vibrational levels are compared to the signals following v=8 excitation. The branching ratio for b 1Σg+ state production following O2 collisions is approximately constant for v=5–8, and decreases by ∼30% for v=9. This decrease in the production of the b 1Σg+ state is attributed to the opening of a reactive channel to produce O atoms and ozone.