Rotationally inelastic scattering of OH by molecular hydrogen: Theory and experiment

Abstract

We present an experimental and theoretical investigation of rotationally inelastic transitions of OH, prepared in the X 2 Π, v = 0, j = 3/2 F 1 f level, in collisions with molecular hydrogen (H 2 and D 2 ). In a crossed beam experiment, the OH radicals were state selected and velocity tuned over the collision energy range 75-155 cm −1 using a Stark decelerator. Relative parity-resolved state-to-state integral cross sections were determined for collisions with normal and para converted H 2 . These cross sections, as well as previous OH-H 2 measurements at 595 cm (2010)], were compared with the results of quantum scattering calculations using recently determined ab initio potential energy surfaces [Ma et al., J. Chem. Phys. 141, 174309 (2014)]. Good agreement between the experimental and computed relative cross sections was found, although some structure seen in the OH( j = 3/2 F 1 f → j = 5/2 F 1 e) + H 2 ( j = 0) cross section is not understood. C 2015 AIP Publishing LLC. [http://dx

Recent Advances in Development and Applications of the Mixed Quantum/Classical Theory for Inelastic Scattering

“…Collision of a molecule with another molecule (or an atom) in gas phase environment is a fundamental physical process important in a broad variety of chemical phenomena, ranging from astrochemistry that occurs on galactic sizes, 1,2 to atmospheric chemistry, 3,4 to combustion processes in the man-made engines, 5,6 and to microfabricated traps cooled down to ultralow temperatures. 7,8 At first glance the inelastic scattering process might look simple: two collision partners exchange energy by means of the interaction potential, but complexity is hidden in the details.…”

The hyperfine excitation of OH radicals by He

“…They found that OH(X)-H 2 looks more like OH(X)−Ne than OH(X)−He, and the OH−H 2 minimum is around 3 times deeper than in the OH(X)−He. This new PES was successfully tested for the study of OH(X)−H 2 rotationally-resolved collisions [38]. The extension of that work to OH(X)−H 2 hyperfine-resolved collisions will provide an important test for the current models for OH masers.…”

Observation of quantum dynamical resonances in near cold inelastic collisions of astrophysical molecules

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