A consensus view of the temperature dependence of the gas phase reaction: OH + HBr → H₂O + Br

Abstract

The temperature dependence of the rate coefficient for the reaction, OH + HBr has been reinvestigated at low temperatures (T = 48-224 K) by using uniform supersonic flow reactors with laser induced fluorescence detection. This paper presents two forms of global fits: k(T) = 1.11 × 10 −11 (T/298) −0.91 cm 3 s −1 and k(T) = 1.06 × 10 −11 (T/298) −1.09 exp( −10.5 K T ) cm 3 s −1 , both of which accurately describe the temperature dependence of the rate coefficient for the title reaction within the temperature range 20-350 K. These fits indicate that at temperatures below 200 K, the rate coefficient for this reaction shows inverse temperature dependence, while above 200 K the reaction shows insignificant temperature dependence.

Kinetics of low-temperature transitions and a reaction rate theory from non-equilibrium distributions

“…These processes can be classified as anti-Arrhenius. In a gasphase reaction the anti-Arrhenius behaviour is frequently found in molecule-radical reactions [126][127][128][129][130][131]. Among these processes, the OH + HBr → H 2 O + Br reaction is one of the most studied experimentally.…”

Inhibition of hydrogen oxidation by HBr and Br2

“…The HBr+OH reaction (R4) has an unusual temperature dependence at very low temperatures, but its rate constant is independent of temperature above 200 K [131].…”

Quantum dynamics study of energy requirement on reactivity for the HBr + OH reaction with a negative-energy barrier

“…In order to converge the rate constants up to 500 K to compare with the experimental results2345678910111213, the reaction probabilities of the ground vibrational state including 6 HBr rotational excitation states ( j 1max  = 5) and 3 OH rotational excitation states ( j 2max  = 3) were calculated.…”

“…Moreover, the rate constants were also measured at the temperature ranges 249–4167, 23–2958, 76–2429, 230–36010, 120–22411, 20–35012, 53–135 K13, and at a high temperature of 1925 K14. Among them, four studies4101113 have also measured the rate constants for the isotopomers system and found the primary kinetic isotope effect (KIE) is independent of temperature between 53 and 135 K13.…”

“…Thus, in this paper, we carry out the first, full-dimensional, quantum dynamics time-dependent, wave-packet study on the PES developed by Bowman’s group. Our purpose of the present work is to (1) calculate the thermal rate constants over the temperature range of 5–500 K and compare our six degrees of freedom (6DOF) results with experiments2345678910111213 and the QCT results24, see the relationship of the rate constants with the temperature; (2) investigate the energy efficiency of the translational, vibrational, and rotational energy on a negative-energy barrier.…”