Reaction of OH and NO at Low Temperatures in the Presence of Water: the Role of Clusters
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Matthias Liessmann
Abstract
There has been a lot of speculation about the role of water in gas phase reactions involving neutrals, radicals and ions. The reaction of NO and OH has attracted a lot of attention in the past due to its relevance for ozone chemistry in the atmosphere. In the present contribution we report low temperature measurements of the recombination of OH and NO at low temperatures in Laval nozzle expansions between 300 K and 60 K. We find an increase of the bimolecular rate constant in the presence of water of up to 40%. This effect has been attributed to water molecules acting either as an efficient collider releasing energy from the intermediate (in collisions) or – which is more likely for the present experimental conditions – as a cluster partner of the reaction intermediate HONO that also dissipates energy via cluster dissociation, which can in turn both stabilize the reaction intermediate, decrease back reaction to OH and NO, and enh ance finally the overall reaction to the products. The supersaturation of water vapor in the cold Laval nozzle expansion strongly favors the formation of clusters in the nozzle throat; their exact concentration is, however, difficult to estimate due to non-equilibrium conditions. The possible role of clusters in the recombination of OH and NO is investigated using ab initio molecular dynamics calculations. Beyond the reaction intermediate HONO and intramolecular proton transfer events also transient HOON was observed in the theoretical study.
© by Oldenbourg Wissenschaftsverlag, Leipzig, Germany
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- Relaxation Dynamics of Electronically Excited C60− in o-Dichlorobenzene and Tetrahydrofuran Solution
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- Thermochemistry and Kinetics for 2-Butanone-3yl Radical (CH3C(=O)CH•CH3) Reactions with O2
- Experimental and Modelling Study of the Unimolecular Thermal Decompostion of CHF3
- Combustion Chemistry of the Butane Isomers in Premixed Low-Pressure Flames
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- Femtosecond interferometry of molecular dynamics – the role of relative and absolute phase of two individual laser pulses
- Photodecarbonylation of Diphenylcyclopropenone – a Direct Pathway to Electronically Excited Diphenylacetylene?
- Yield of HO2 Radicals in the OH-Initiated Oxidation of SO2
- Pyrolysis of Ethyl Iodide as Hydrogen Atom Source: Kinetics and Mechanism in the Temperature Range 950–1200 K
- Reaction of OH and NO at Low Temperatures in the Presence of Water: the Role of Clusters
Articles in the same Issue
- Preface
- OH and NH Stretching Vibrational Relaxation of Liquid Ethanolamine
- Transient anisotropy in degenerate systems: A semi-classical approach
- First Cavity Ring-Down Spectroscopy HO2 Measurements in a Large Photoreactor
- Relaxation Dynamics of Electronically Excited C60− in o-Dichlorobenzene and Tetrahydrofuran Solution
- 3CH2 + O2: Kinetics and Product Channel Branching Ratios
- What Do We Know About the Iconic System CH3 + CH3 + M ↔ C2H6 + M?
- Thermochemistry and Kinetics for 2-Butanone-3yl Radical (CH3C(=O)CH•CH3) Reactions with O2
- Experimental and Modelling Study of the Unimolecular Thermal Decompostion of CHF3
- Combustion Chemistry of the Butane Isomers in Premixed Low-Pressure Flames
- Characterization of Rhodamine 6G Release in Electrospray Ionization by Means of Spatially Resolved Fluorescence Spectroscopy
- Femtosecond interferometry of molecular dynamics – the role of relative and absolute phase of two individual laser pulses
- Photodecarbonylation of Diphenylcyclopropenone – a Direct Pathway to Electronically Excited Diphenylacetylene?
- Yield of HO2 Radicals in the OH-Initiated Oxidation of SO2
- Pyrolysis of Ethyl Iodide as Hydrogen Atom Source: Kinetics and Mechanism in the Temperature Range 950–1200 K
- Reaction of OH and NO at Low Temperatures in the Presence of Water: the Role of Clusters
