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

We present an experimental and theoretical investigation of rotationally inelastic transitions of OH, prepared in the X-2 Pi, 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(-1) collision energy by Schreel and ter Meulen [J. Chem. Phys. 105, 4522 (1996)], and OH-D-2 measurements for collision energies 100-500 cm(-1) by Kirste et al. [Phys. Rev. A 82, 042717 (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.