Fast multiquantum vibrational relaxation of highly vibrationally excited O2

A significant fraction of the initial population of highly vibrationally excited oxygen molecules X 3Σg−(v⩾23) prepared by stimulated emission pumping, relaxes to much lower vibrational levels (Δv≈−9). The time scale is much shorter than the known collisional lifetimes of the intervening vibrational levels and thus a sequential single-quantum relaxation mechanism can be explicitly ruled out. State-to-state measurements after preparation of v=28 and 30 provide the final-vibrational state population distribution resulting from relaxation of these two states. For v=28(30), at least 38%(7.9%) of the initially prepared population, undergoes multiquantum vibrational relaxation. The observed multiquantum relaxation explains, at least in part, the previously reported “dark channel” for relaxation of vibrational levels higher than v=26, but does not exclude the possibility of reactive scattering (forming ozone) for the remaining fraction of highly vibrationally excited molecules. We discuss possible explanations o...

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