Electronic quenching of OH A2Σ+ radicals in collisions with molecular hydrogen

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

“…The nonreactive quenching channel has also been investigated recently in Lester's experiments, utilizing a pump-probe approach in the collisional region of a supersonic free-jet expansion. [11][12][13][14] The OH products were generated with significant rotational excitation, but small degree of vibrational excitation, and the preference for reactive quenching over nonreactive quenching by roughly 7 to 1 was also discovered by the Lester group. 13 Theoretically, Yarkony and co-workers performed stateaveraged multiconfigurational self-consistent field/ configuration interaction calculations to determine the conical intersections ͑CoIs͒ of the potential energy surfaces ͑PESs͒ relevant to this quenching.…”

“…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.…”

Reactive quenching of OD A 2Σ+ by H2: Translational energy distributions for H- and D-atom product channels

“…[4][5][6][7] Several empirical models have been proposed to explain the quenching phenomena, 2,[8][9][10][11] yet only recently has the mechanism for quenching of OH A 2 + by even simple molecular partners (H 2 , N 2 ) become evident from experiment and first-principles theory. [12][13][14][15][16][17][18][19][20][21][22][23][24] In order to elucidate new information about the mechanism, recent experimental studies have focused on the outcomes of collisional quenching. Two possible outcomes for quenching of OH A 2 + by H 2 There is insufficient energy released upon quenching to access higher-energy three-body breakup channels.…”

“…Two possible outcomes for quenching of OH A 2 + by H 2 There is insufficient energy released upon quenching to access higher-energy three-body breakup channels. Previous investigations focused on the quantum state distribution of the OH X 2 products from nonreactive quenching under single collision conditions for several isotopic variants of this system, [13][14][15]21 with the most recent study focused on nonreactive quenching of OD A 2 + by H 2 . 19 The OH/D X 2 products were found to exhibit extensive rotational excitation and strong -doublet selectivity with minimal vibrational excitation.…”

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

“…In general, the quenching cross sections exhibit a negative dependence on temperature, indicating that attractive forces are important. 17,[24][25][26] Background experimental and theoretical information on the OH A 2 ⌺ + +H 2 and N 2 systems follows after a brief discussion of related work on quenching of NO A 2 ⌺ + . 4,10,11,17 A number of different empirical models have been proposed to rationalize quenching cross sections and other trends deduced from kinetic measurements.…”