Lambda-Dublett Spezifische Untersuchung von Rotations- und Feinstrukturuebergaengen des OH bei Stoessen MIT H2 (Lambda-Doublet-Specific Investigation of Rotational and Fine-Structure Transitions of OH in Collisions with H2)

摘要

The inelastic scattering of OH on H2 was investigated in a crossed molecular beam experiment which allowed the measurement of the inelastic cross sections for rotational and fine-structure transitions. The scattered OH-molecule was observed by laser induced fluorescence, allowing determination of the energetic state of the lambda-doublet components. The measurements show a different occupation of the lambda-doublet components for almost all rotational states. Comparative measurements on the system OH-D2 show no essential differences in the relative magnitudes of the inelastic cross sections in OH-H2 and OH-D2. The cross sections, averaged over the lambda-doublet components, are well reproduced by scattering calculations, which also reveal the anti-inversion found in the experiment. The calculated and measured cross sections do not always agree well for all transitions. Test calculations determined the dependence of the cross sections on difference potential and coupling structure of the OH molecule. Rate constants for OH rotational transitions were obtained. The experiment shows that astronomical OH masers can be pumped by collisions.