Inelastic state-to-state scattering of OH (Π3∕22,J=3∕2,f) by HCl

Abstract

Parity resolved state-to-state cross sections for inelastic scattering of OH (X2Pi) by HCl were measured in a crossed molecular beam experiment at the collision energy of 920 cm(-1). The OH (X2Pi) radicals were prepared in a single quantum state, Omega=3/2, J=3/2, MJ=3/2, f, by means of electrostatic state selection in a hexapole field. The rotational distribution of the scattered OH radicals by HCl was probed by saturated LIF spectroscopy of the 0-0 band of the A 2Sigma+ - X 2Pi transition. Relative state-to-state cross sections were measured for rotational excitations up to J=9/2 within the Omega=3/2 spin-orbit manifold and up to J=7/2 within the Omega=1/2 spin-orbit manifold. A propensity for spin-orbit conserving transitions was found, but no propensity for excitation into a particular Lambda-doublet component of the same rotational state was evident. The data are presented and discussed in comparison with results previously obtained for collisions of OH with CO (Ecoll=450 cm(-1)) and N2 (Ecoll=410 cm(-1)) and with new data we have measured for the OH+CO system at a comparable collision energy (Ecoll=985 cm(-1)). This comparison suggests that the potential energy surface (PES) governing the interaction between OH and HCl is more anisotropic than the PES's governing the intermolecular interaction of OH with CO and N2.

Ab initio computed diabatic potential energy surfaces of OH–HCl

“…8 Also rotationally inelastic state-to-state scattering cross sections of OH͑ 2 ⌸ 3/2 ͒ in collision with HCl were measured recently. 1 To support this experimental work, computations on the same cross sections are underway in our group. In addition, computations on the bound states of the van der Waals complex OH͑ 2 ⌸͒-HCl are planned.…”

“…The comparison of experimental and theoretical cross sections gives a thorough check on computed results and contributes importantly to the understanding of the physical origin of propensity rules observed in Ref. 1. The scattering and bound state calculations are based on the expanded potential energy surfaces reported in the present article.…”

“…Several experimental and computational studies have been devoted to this reaction, see Ref. 1 for a survey of the literature. An important aspect of the theoretical studies [2][3][4][5][6] is the potential energy surface for the reaction which was investigated either through the use of semi-empirical models or by means of ab initio electronic structure calculations.…”

State-to-state inelastic scattering of OH by HI: A comparison with OH–HCl and OH–HBr

“…[10][11][12] Two pulsed 50 s full width at half maximum duration molecular beams ͑Jordan͒ operating at a repetition rate of 10 Hz expand supersonically in perpendicular directions. [10][11][12] Two pulsed 50 s full width at half maximum duration molecular beams ͑Jordan͒ operating at a repetition rate of 10 Hz expand supersonically in perpendicular directions.…”

Kinetics of the OH+HCl→H2O+Cl reaction: Rate determining roles of stereodynamics and roaming and of quantum tunneling

“…An alternative source of important information comes from molecular beam scattering experiments with oriented reactants, however, limited to the nonreactive case: Cireasa et al report stereodynamical features in the inelastic collisions between OH and HCl molecule, showing that H‐end attack is favored for the inelastic collision system. They define a “steric asymmetry factor” and found it negative, in contrast with the analogous four‐body reaction, OH + HBr, for which the O‐end attack is more favorable by a factor three over that at the H‐end …”