Inelastic collisions of OH (2Π) with H2: Comparison between theory and experiment including rotational, fine structure, and Λ-doublet transitions

Detailed cross section calculations for inelastic collisions of OH (2Π) in the ground state j=3/2, Ω̄=3/2 with H2 are presented using an ab initio potential energy surface without adjustable parameters. The OH molecular wave function is described within the intermediate coupling case. The results are compared with recent experiments. The agreement is satisfactory for the final rotational state distributions within both the Ω̄=3/2 and the Ω̄=1/2 ladder. Also the relative magnitude of Ω̄=1/2 and 3/2 cross sections is in good accord with experiment and thus indicates that the difference potential VA′-VA″ is realistically described by the ab initio calculation. The dynamical calculations yield prefential excitation of one Λ-doublet state. The extent of this preference increases with j and is larger for Ω̄=3/2 in qualitative but not quantitative agreement with experiment. Possible interpretations in terms of the potential energy surfaces are briefly discussed.