O + OH → O 2 + H : A key reaction for interstellar chemistry. New theoretical results and comparison with experiment

Abstract

Accurate quantum mechanical calculations of differential and integral cross sections and rate constant for the reaction using an ab initio potential energy surface

Accurate time dependent wave packet calculations for the N + OH reaction

“…This behavior, which is characteristic of barrierless exothermic reactions, is similar, among others, to the radical-radical OH + O reaction, as recently reported by some groups. 38,39 The agreement between the WP and QCT excitation functions is quite good for the whole range of collision energies, except for low energies, below 0.05 eV, where the WP results are considerably larger than the QCT ones. The reason of the faster increase of the WP cross section is the resonances appearing near the threshold.…”

Role of OH radicals in the formation of oxygen molecules following vacuum ultraviolet photodissociation of amorphous solid water

“…These OH͑v = 0 and 1,T trans = 7500 K͒ can proceed in endothermic reactions on ASW surface. 16 21 pointed out a possibility of the nonadiabatic transition for the OH+ O reaction. The potential energy surface of OH+ O reaction corresponding to the electronically excited 2AЈ state correlates only with the O 2 ͑a 1 ⌬ g ͒ + H product channel through the electronically excited state of the HO 2 ͑2AЈ͒ complex, but nonadiabatic electronic relaxation of this complex to the lowest 2AЉ state can provide O 2 ͑X 3 ⌺ g − ͒ + H product channel.…”

“…[18][19][20] From the fact that OH͑v = 0 and 1͒ and O͑ 3 P͒ are formed with large excess energy via reactions ͑1͒, ͑3͒, and ͑4͒, 15 Reaction ͑5͒ is a barrierless process in the gas phase. 21 OH͑v =1͒ has a sufficient vibration energy of 43 kJ mol −1 to proceed in reaction ͑6͒. 22 In fact, Lunt et al 23 …”

Oxygen depletion in dense molecular clouds: a clue to a low O2abundance?

“…The study of this reaction has attracted considerable experimental attention (Howard & Smith 1980, 1981Lewis & Watson 1980;Brune et al 1983;Smith & Stewart 1994;Robertson & Smith 2002Carty et al 2006), and there have also been a large number of theoretical studies using a variety of methods (Harding et al 2000;Troe & Ushakov 2001;Xu et al 2007;Lin et al 2008;Lique et al 2009;Quéméner et al 2009;Maergoiz et al 2004;Jorfi et al 2009;Li et al 2010). The experimental rate constant is well determined between 140 and 300 K decreasing from 7 × 10 −11 cm 3 molecule −1 s −1 at 140 K to 3 × 10 −11 cm 3 molecule −1 s −1 at 300 K. Between 40 and 140 K, the reaction has been studied in a CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme) apparatus (Carty et al 2006) leading to a value of around 3.5(±1.0) × 10 −11 cm 3 molecule −1 s −1 which however has large uncertainties.…”

“…Time-dependent wave packet methods are unsuitable for the low temperature regime leading to an unreliably low rate that is con-1 http://kida.obs.u-bordeaux1.fr stant at low temperature (Xu et al 2007;Lin et al 2008). Timeindependent quantum mechanical calculations, supposed to be the more accurate at low temperature, have been applied to this system leading to value around 4 × 10 −11 cm 3 molecule −1 s −1 at 10 K (Lique et al 2009;Quéméner et al 2009). However, they neglect spin orbit coupling and electronic fine structure of O and OH, as well as surface hopping dynamics between the ground and excited potentials at large O-OH distances.…”