On the theory of the reaction rate of vibrationally excited CO molecules with OH radicals

Abstract

The dependence of the rate of the reaction CO+ OH→ H+CO 2 on the CO-vibrational excitation is treated here theoretically. Both the Rice-Ramsperger-Kassel-Marcus ͑RRKM͒ rate constant k RRKM and a nonstatistical modification k non ͓W.-C. Chen and R. A. Marcus, J. Chem. Phys. 123, 094307 ͑2005͒.͔ are used in the analysis. The experimentally measured rate constant shows an apparent ͑large error bars͒ decrease with increasing CO-vibrational temperature T v over the range of T v 's studied, 298-1800 K. Both k RRKM ͑T v ͒ and k non ͑T v ͒ show the same trend over the T v -range studied, but the k non ͑T v ͒ vs T v plot shows a larger effect. The various trends can be understood in simple terms. The calculated rate constant k v decreases with increasing CO vibrational quantum number v, on going from v =0 to v = 1, by factors of 1.5 and 3 in the RRKM and nonstatistical calculations, respectively. It then increases when v is increased further. These results can be regarded as a prediction when v state-selected rate constants become available.

The Sea Spray Chemistry and Particle Evolution study (SeaSCAPE): overview and experimental methods

“…The OH exposure is determined using the rate coefficient of CO + OH ( k OH+CO, 298K = 1.5 × 10 −13 cm 3 molec −1 s −1 ), assuming pseudo-first order kinetics. 36 The OH exposure can be converted to “days of equivalent aging” using typical tropospheric OH concentrations ([OH] = 1.0 × 10 6 molec cm −3 ). 37 O 3 concentrations were monitored downstream of each of the OFRs using an O 3 analyzer (Model 202 and Model 106-L, 2B Technologies).…”

Molecular Dynamics Study of Combustion Reactions in a Supercritical Environment. Part 2: Boxed MD Study of CO + OH → CO2 + H Reaction Kinetics

“…More detailed investigations of revealed that HOCO is formed in vibrationally excited state HOCO*. ,,− This hot intermediate may further deactivate in one of three channels: stabilization by a third particle M in , redissociation back to the reactants in , and product formation in Several studies ,,,,, focused on the vibrationally excited reactants: OH* and CO*. The rate constant for was shown to decrease ,, when CO* is involved but to increase with OH* involvement.…”

“…More detailed investigations of revealed that HOCO is formed in vibrationally excited state HOCO*. ,,− This hot intermediate may further deactivate in one of three channels: stabilization by a third particle M in , redissociation back to the reactants in , and product formation in Several studies ,,,,, focused on the vibrationally excited reactants: OH* and CO*. The rate constant for was shown to decrease ,, when CO* is involved but to increase with OH* involvement. Participation of the third particle in results in the rate increase for the overall reaction with increasing pressure. ,,,,,,,,− The nature of M is also important: while He diluent was found to be less efficient, H 2 and SF 6 increase reaction rate to a greater extent. − At the same time, O 2 /Ar mixture has no effect .…”

“…14,59,67−69 This hot intermediate may further deactivate in one of three channels: 39 stabilization by a third particle M in R4, redissociation back to the reactants in R5, and product formation in R6 Several studies 70,55,5,68,71,39 focused on the vibrationally excited reactants: OH* and CO*. The rate constant for R1 was shown to decrease 5,56,68 when CO* is involved but to increase with OH* involvement. Participation of the third particle in R4 results in the rate increase for the overall reaction R1 with increasing pressure.…”

The Sea Spray Chemistry and Particle Evolution Study (SeaSCAPE): Overview and Experimental Methods

“…The OH exposure at each lamp intensity was determined by introducing carbon monoxide to the OFR and measuring the drop in CO concentration due to oxidation using a CO analyzer (APMA-370, Horiba Ltd). The OH exposure is determined using the rate coefficient of CO + OH (kOH + CO, 298K = 1.5×10 -13 cm 3 molec -1 s -1 ), assuming pseudo-first order kinetics (Chen and Marcus, 2006). The OH exposure can be converted to "days of equivalent aging" using typical tropospheric OH concentrations ([OH] = 1.0 × 10 6 molec•cm -3 ) (Wolfe et al, 2019).…”