Rotational relaxation of the A1π(ν′ = 13, J′ = 13+) state of 13C16O by various gases

Abstract

Rotational relaxation of the A1π (ν′ = 13, J′ = 13+) state of 13C16O was studied in the presence of H2, D2, He, Ne, Ar, Xe, N2, CO, 13C16O, and 12C18O. The rotational relaxation cross sections Σσ13 → J′, in cm2 × 1016 and in the above order, were: 19 ± 1, 27 ± 1, 23 ± 1, 32 ± 1, 55 ± 2, 14 ± 1, 43 ± 3, 69 ± 5, 23 ± 1, and 100 ± 15. The rotational relaxation probabilities per gas-kinetic collision correlate with the square root of the reduced mass, except for Xe and the CO isotopic molecules. The latter molecules have several electronic states accessible at this energy. Their rotational relaxation cross sections depend on the magnitude of their respective electronic quenching cross sections, in a manner indicating preemption by fast electronic–electronic energy transfer.