State-resolved distribution of OH X Π2 products arising from electronic quenching of OH A Σ2+ by N2

Abstract

The nascent OH X (2)Pi product state distribution arising from collisional quenching of electronically excited OH A (2)Sigma(+) by N(2) has been determined using a pump-probe technique. The majority of OH X (2)Pi products are observed in their lowest vibrational level, v(")=0, with significantly less population in v(")=1. The OH (v(")=0) products are generated with a substantial degree of rotational excitation, peaking around N(")=18, with an average rotational energy of approximately 6500 cm(-1). A preference is found for the OH Pi(A(')) Lambda-doublet, indicating some degree of ppi orbital alignment. The branching fraction into OH X (2)Pi product states demonstrates that nonreactive quenching is the dominant decay pathway for quenching of OH A (2)Sigma(+) by N(2). The topography of the conical intersection region that couples the electronically excited and ground state potential energy surfaces is also examined theoretically. The rotational excitation of the OH X (2)Pi products and branching fraction are found to be dynamical signatures of nonadiabatic passage through the conical intersection region.

The influence of excited state topology on wavepacket delocalization in the relaxation of photoexcited polyatomic molecules

“…The influence of CIs and their topography on nuclear dynamics is a subject that has been investigated before. 44,[58][59][60][61][62][63] Here, we only focus on the delocalization of the WP.…”

Quasiclassical trajectory study of the postquenching dynamics of OH AΣ2+ by H2/D2 on a global potential energy surface

“…The quenching of OH radicals in their excited A 2 ⌺ + state by H 2 ͑D 2 ͒ to nonreactive, OH+ H 2 ͑D 2 ͒, and reactive, H 2 O+H ͑HOD+ D and D 2 O+H͒, products has been the focus of extensive experimental and theoretical studies in the past few years [8][9][10][11][12][13][14][15][16][17][18][19] and is one of the most thoroughly studied systems for nonadiabatic dynamics. In experiments, Lester and co-workers 9,10 investigated the reactive channel with H 2 and D 2 using two-photon laser-induced fluorescence ͑LIF͒ detection of the H and D atom products and analyzing the Doppler profiles.…”

Electronic Quenching of OH A 2Σ+ Induced by Collisions with Kr Atoms

“…Characteristics of the reactive (forming new products) and/or nonreactive (returning OH to its ground X 2  state) events have been studied for several quenching partners (H 2 , D 2 , N 2 , CO, CO 2 , O 2 ). 11,[13][14][15][16][17][18][19][20] Branching fractions have also been determined. [14][15][16][17][18][19][20] The importance of the nonreactive OH X 2  (v″=0-2) pathways varies significantly with collision partner, ranging, for example, from 12% for H 2 to 88% for N 2 .…”

“…23 The forces in the region of conical intersection indicate a propensity toward nonreactive products with a large degree of OH rotation and comparatively less OH vibration with N 2 than predicted for H 2 , which is consistent with experimental results. 17 The majority of previous experimental and theoretical studies for the OH (X 2 , A 2  + ) +…”