Measurement of absolute state-to-state rate constants for collision-induced transitions between spin-orbit and rotational states of NO(X ²Π, v=2)

Abstract

Using a pulsed, time resolved IR-UV double resonance technique, we have measured initial and final state specific rates for collision-induced rotational and spin-orbit transitions in NO in its (X 2Π, v=2) vibronic state. A systematic study of the rates was done for initial and final rotational states with J between 1/2 and 35/2, for both Ω=1/2 and the Ω=3/2 spin-orbit components of the X 2Π state. Collision partners were room temperature NO, He, Ar, N2, CO and SF6. No propensity rules favoring ΔΩ=0 or ΔJ=0, ±1 were observed, except in NO-He collisions, where ΔΩ=0 was favored. The state-to-state rates do not vary much with initial state and fall off slowly with increasing ΔJ. Total cross sections for collision-induced rotational transitions were found to be tens of Å2, insensitive to initial state, and correlated with the size of the collision partner. © 1982 American Institute of Physics.