title: Electronic quenching of OH A 2Sigma+ radicals in single collision events with H2 and D2: a comprehensive quantum state distribution of the OH X 2Pi products.
abstract: A pump-probe laser-induced fluorescence technique has been used to examine the nascent OH X (2)Pi product state distribution arising from non-reactive quenching of electronically excited OH A (2)Sigma(+) by molecular hydrogen and deuterium under single-collision conditions. The OH X (2)Pi products were detected in v''=0, 1 and 2; the distribution peaks in v''=0 and decreases monotonically with increasing vibrational excitation. In all vibrational levels probed, the OH X (2)Pi products are found to be highly rotationally excited, the distribution peaking at N''=15 when H(2) was used as the collision partner and N''=17 for D(2). A marked propensity for production of Pi(A') Lambda-doublet levels was observed, while both OH X (2)Pi spin-orbit manifolds were equally populated. These observations are interpreted as dynamical signatures of the nonadiabatic passage of the OH + H(2)/D(2) system through the seams of conical intersection that couple the excited state (2 (2)A') and ground state (1 (2)A') surfaces.
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
authors.forename: Logan P
authors.initials: LP
authors.lastname: Dempsey
authors.forename: Craig
authors.initials: C
authors.lastname: Murray
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Cleary
authors.forename: Marsha I
authors.initials: MI
authors.lastname: Lester
mesh_terms: D003903:Deuterium / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry*; D008956:Models, Chemical; D011789:Quantum Theory
chemical_list: D017665:Hydroxyl Radical; D006859:Hydrogen; D003903:Deuterium