HOx, NOx, and ClOx: Their Role in Atmospheric Photochemistry

1974 ◽  
Vol 52 (8) ◽  
pp. 1582-1591 ◽  
Author(s):  
Steven C. Wofsy ◽  
Michael B. McElroy
Keyword(s):  
Gas Phase ◽  
Phase Reaction ◽  
Dominant Form ◽  
Supersonic Aircraft ◽  
Mesospheric Ozone ◽  
Ozone Photochemistry ◽  
Odd Nitrogen ◽  
Good Agreement ◽  
Odd Oxygen

Sources of atmospheric odd nitrogen and hydrogen are reviewed and their role m ozone photochemistry is discussed. A model, containing few adjustable parameters, gives good agreement with observed distributions of stratospheric and mesospheric ozone. Nitric oxide emitted by supersonic aircraft would lead to a significant reduction in the concentration of atmospheric ozone if the globally averaged source of NO should exceed 2 × 107 molecules cm−2 s−1. A traffic model projected by Broderick etal. for 1990 could lead to a reduction of about 2% in the column density of O3.Sources of atmospheric chlorine are discussed. It is argued that HCl should be the dominant form of atmospheric chlorine and that it is produced mainly from aerosols of marine origin. The atmospheric source strength is about 2 × 108 tons per year according to Chesselet etal. and HCl may be removed by gas phase reaction with NH3. The role of chlorine compounds as a catalyst for recombination of odd oxygen is discussed and shown to play no major role in the normal atmosphere. Reactions of OH and HO2 with O3 may provide an important sink for tropospheric odd oxygen such that O3 may not be a passive tracer for tropospheric motions.

scholarly journals Role of (H2O)n (n = 1–2) in the Gas-Phase Reaction of Ethanol with Hydroxyl Radical: Mechanism, Kinetics, and Products

ACS Omega ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 5805-5817 ◽  
Author(s):  
Li Xu ◽  
Narcisse T. Tsona ◽  
Shanshan Tang ◽  
Junyao Li ◽  
Lin Du
Keyword(s):  
Hydroxyl Radical ◽  
Gas Phase ◽  
Radical Mechanism ◽  
Phase Reaction ◽  
Gas Phase Reaction

Impact of water on the BrO + HO2 gas-phase reaction: mechanism, kinetics and products

2019 ◽  
Vol 21 (36) ◽  
pp. 20296-20307 ◽  
Author(s):  
Narcisse T. Tsona ◽  
Shanshan Tang ◽  
Lin Du
Keyword(s):  
Reaction Mechanism ◽  
Gas Phase ◽  
Hydrogen Abstraction ◽  
Phase Reaction ◽  
Gas Phase Reaction

The role of water in preventing the barrierless hydrogen abstraction in the BrO + HO2 reaction is highlighted.

Thermochemistry and Kinetics of Gas-Phase Reactions Relevant to the CVD of Coatings: New Data for Process Models

1998 ◽  
Vol 555 ◽  
Author(s):  
M. D. Allendorf ◽  
C. F. Melius ◽  
A. H. McDaniel
Keyword(s):  
Gas Phase ◽  
Hexagonal Boron Nitride ◽  
Precursor Chemistry ◽  
Process Models ◽  
Phase Reaction ◽  
Gas Phase Reactions ◽  
Flow Reactors ◽  
Powerful Approach

AbstractUnderstanding the role of gas-phase reactions is an important step in the development of useful CVD process models. In this article, we review the general types of gas-phase reactions that can occur and discuss quantum-chemistry techniques for predicting their thermochemistry and kinetics. We also describe the use of high-temperature flow reactors to measure gas-phase reaction kinetics. Coupling these theoretical and experimental methods is a powerful approach to the characterization of CVD precursor chemistry. We illustrate this in a discussion of the reaction between BC13 and NH3, which is important in the deposition of hexagonal boron nitride coatings.

scholarly journals Kinetic and Mechanistic Studies for the Gas-phase Reaction of Ozone with 2, 3-Dimethyl-2-Butene and 1, 3-Butadiene

2017 ◽  
Vol 14 (3) ◽  
pp. 547-556
Author(s):  
Baghdad Science Journal
Keyword(s):  
Double Bond ◽  
Gas Phase ◽  
Rate Coefficients ◽  
Phase Reaction ◽  
Atmospheric Conditions ◽  
Absolute Rate ◽  
Mechanistic Studies ◽  
Methyl Group ◽  
Gas Phase Reaction ◽  
Good Agreement

The reactions of ozone with 2,3-Dimethyl-2-Butene (CH3)2C=C(CH3)2 and 1,3-Butadiene CH2=CHCH=CH2 have been investigated under atmospheric conditions at 298±3K in air using both relative and absolute rate techniques, and the measured rate coefficients are found to be in good agreement in both techniques used. The obtained results show the addition of ozone to the double bond in these compounds and how it acts as function of the methyl group substituent situated on the double bond. The yields of all the main products have been determined using FTIR and GC-FID and the product studies of these reactions establish a very good idea for the decomposition pathways for the primary formed compounds (ozonides) and give a good information for the effect of the methyl group on the degradation pathways. The results have been discussed from the view point of their importance in the atmospheric oxidation of these pollutants.

scholarly journals Role of glyoxal in SOA formation from aromatic hydrocarbons: gas-phase reaction trumps reactive uptake

2011 ◽  
Vol 11 (11) ◽  
pp. 30599-30625 ◽  
Author(s):  
S. Nakao ◽  
Y. Liu ◽  
P. Tang ◽  
C.-L. Chen ◽  
J. Zhang ◽  
...  
Keyword(s):  
Aromatic Hydrocarbon ◽  
Gas Phase ◽  
Phase Reaction ◽  
Oh Radical ◽  
Near Surface ◽  
Aerosol Mass Spectrometer ◽  
Seed Particles ◽  
Aerosol Mass ◽  
Experimental Approaches

Abstract. This study evaluates the significance of glyoxal acting as an intermediate species leading to SOA formation from aromatic hydrocarbon photooxidation under humid conditions. Rapid SOA formation from glyoxal uptake onto aqueous (NH4)2SO4 seed particles is observed; however, glyoxal did not partition to SOA or SOA coated aqueous seed during all aromatic hydrocarbon experiments (RH up to 80%). Glyoxal is found to only influence SOA formation by raising hydroxyl (OH) radical concentrations. Four experimental approaches supporting this conclusion are presented in this paper: (1) increased SOA formation and decreased SOA volatility in the toluene + NOx photooxidation system with additional glyoxal was reproduced by matching OH radical concentrations through H2O2 addition; (2) glyoxal addition to SOA seed formed from toluene + NOx photooxidation did not increase observed SOA volume; (3) SOA formation from toluene + NOx photooxidation with and without deliquesced (NH4)2SO4 seed resulted in similar SOA growth, consistent with a coating of SOA preventing glyoxal uptake onto deliquesced (NH4)2SO4 seed; and (4) the fraction of a C4H9+ fragment (observed by Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer, HR-ToF-AMS) from SOA formed by 2-tert-butylphenol (BP) oxidation was unchanged in the presence of additional glyoxal despite enhanced SOA formation. This study suggests that glyoxal uptake onto aerosol is minor when the surface (and near-surface) of aerosols are primarily composed of secondary organic compounds.

Water-catalysis in the gas phase reaction of dithioformic acid with hydroxyl radical: global reaction route mapping of oxidative pathways for hydrogen abstraction

RSC Advances ◽  
2015 ◽  
Vol 5 (63) ◽  
pp. 50989-50998 ◽  
Author(s):  
Gurpreet Kaur ◽  
Vikas Vikas
Keyword(s):  
Gas Phase ◽  
Hydrogen Abstraction ◽  
Phase Reaction ◽  
Reaction Route ◽  
Gas Phase Reaction ◽  
Catalytic Role ◽  
Global Reaction ◽  
Single Water Molecule ◽  
Quantum Mechanical Computations

Through the advanced quantum mechanical computations, this work investigates the catalytic-role of single water-molecule during hydrogen abstraction, in dithioformic acid, by the OH radical.

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