Homogeneous and Heterogeneous Chemistry in the Stratosphere

Finlayson-Pitts, B. J.

doi:10.1016/b978-012257060-5/50014-9

Cited by 9 publications

(9 citation statements)

References 611 publications

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“…Due to the dependence of the reactive uptake coefficient of NO for reaction 2 on the HNO 3 concentration as shown in Figure , it is concluded that the upper limit of γ(NO→HONO) < 4 × 10 -11 , determined in this study at the lowest NO y concentrations reported so far, is representative for reaction 2 under atmospheric conditions. The value should be strictly considered as an upper limit, because even in the present study, the NO y concentrations used were still much higher than values typically observed in the urban atmosphere . It follows that reaction 2 is insignificant for both heterogeneous HONO formation and possible “renoxification” processes in the atmosphere, in good agreement with the conclusion of Svensson an Ljungström .…”

Section: Atmospheric Implicationsupporting

confidence: 81%

Heterogeneous Reaction of Nitric Acid with Nitric Oxide on Glass Surfaces under Simulated Atmospheric Conditions

2004

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The heterogeneous reaction of nitric acid (HNO3) with nitric oxide (NO) on borosilicate glass surfaces was studied in a flow system at relative humidity levels in the range 21−86%. Reactant concentrations were kept closer to ambient atmospheric levels as compared to all previous studies of this reaction. Within experimental error, no formation of the proposed reaction products nitrous acid (HONO) and nitrogen dioxide (NO2) was observed. Upper limits of the reactive uptake coefficients of NO on borosilicate glass surfaces, covered with ∼1 monolayer of HNO3, were determined: γ(NO→HONO) < 4.0 × 10-11 and γ(NO→NO2) < 2.5 × 10-9. These values are significantly lower than previously reported values, which were determined at higher reactant concentrations. Results obtained upon investigation of the secondary heterogeneous reaction of the proposed product HONO with HNO3 under identical experimental conditions show that HONO should be observed in the study of the reaction HNO3 + NO, if it is formed. Thus, the obtained upper limit γ(NO→HONO) is representative for the reaction HNO3 + NO → HONO + NO2. Under the assumption that the glass surfaces, typically used in laboratory studies of this reaction, are representative for environmental surfaces, the latter reaction is unimportant for atmospheric HONO formation and for a “renoxification” of the atmosphere.

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Section: Atmospheric Implicationsupporting

confidence: 81%

Heterogeneous Reaction of Nitric Acid with Nitric Oxide on Glass Surfaces under Simulated Atmospheric Conditions

2004

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“…However, O 2 can potentially serve as both a third body collision partner in termolecular reactions and a reactant in bimolecular steps, depending on the electronic structure of the reactants and products. 61 In the present experiments, the HONO yields in synthetic air and pure oxygen were significantly higher than that obtained in pure nitrogen (cf. Fig.…”

Section: Discussioncontrasting

confidence: 52%

“…where J(NO 2 ) was calculated numerically incorporating the chemistry of the Leighton equilibrium 61 and recommended rate constants. 62 For all six lamps, a value for J(NO 2 ) of 0.018 s À1 was determined inside the photoreactor.…”

Section: Methodsmentioning

confidence: 99%

The photolysis of ortho-nitrophenols: a new gas phase source of HONO

Bejan

Aal

Barnes

et al. 2006

Phys. Chem. Chem. Phys.

241

296

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Formation of nitrous acid (HONO) in the gas phase has been observed for the first time in a flow tube photoreactor upon irradiation (l = 300-500 nm) of 2-nitrophenol and methyl substituted derivatives using a selective and sensitive instrument (LOPAP) for the detection of HONO. Formation of HONO by heterogeneous NO 2 photochemistry has been excluded, since production of NO 2 under the experimental conditions is negligible. Variation of the surface to volume ratio and the nitrophenol concentration showed that the photolysis occurred in the gas phase indicating that HONO formation is initiated by intramolecular hydrogen transfer from the phenolic OH group to the nitro group. From the measured linear dependence of the HONO formation rate on the reactant's concentration and photolysis light intensity, a non-negligible new HONO source is proposed for the urban atmosphere during the day. Unexpectedly high HONO mixing ratios have been observed recently in several field campaigns during the day. It is proposed that the photolysis of aromatic compounds containing the ortho-nitrophenol entity could help to explain, at least in part, this high contribution of HONO to the oxidation capacity of the urban atmosphere.

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“…Atmospheric aerosols, which have been found to contain a large number of chemical elements and a high content of organic material, also provide sites for chemical reactions to take place (15)(16)(17)(18). Both the air-water interface and the aqueous bulk interior of aerosols contribute to its overall effect.…”

mentioning

confidence: 99%

“…During winter in the polar regions, aerosols grow to form polar stratospheric clouds, which offer a surface for chemical reactions to take place. These reactions convert HCl and ClONO 2 molecules into the photochemically active chlorine and ultimately lead to the destruction of ozone in the stratosphere (16). Additionally, ab initio molecular dynamics simulation results show that the typical timescale for the reaction of the smallest Criegee intermediate, CH 2 OO, with water at the air-water interface is on the order of a few picoseconds, 2-3 orders of magnitude shorter than that in the gas phase.…”

mentioning

confidence: 99%

Production of hydrogen peroxide enabled by microdroplets

Zhu

Francisco

2019

Proc. Natl. Acad. Sci. U.S.A.

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Geometry and dimensionality of a reaction system are known to play an important role in determining the yield as well as the rate of the reaction, especially in simple bimolecular reactions (1-8). Recently, several results have been reported for reactions in small droplets, which include charged microdroplets (3), microdiameter emulsions (2), inverted micelles (4), and the surfaces of aerosol particles (1). It has been found that chemical reactions can be accelerated in water microdroplets (2, 3, 6, 7), which indicates that the surface of aqueous microdroplets provides a unique reaction environment with different thermodynamics and kinetic properties compared to the bulk phase. In PNAS, Lee et al. (8) report experimental evidence that hydrogen peroxide (H 2 O 2) is spontaneously produced from pure water by atomizing bulk water into microdroplets, which does not occur in bulk aqueous solutions. Production of H 2 O 2 increases with

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Homogeneous and Heterogeneous Chemistry in the Stratosphere

Cited by 9 publications

References 611 publications

Heterogeneous Reaction of Nitric Acid with Nitric Oxide on Glass Surfaces under Simulated Atmospheric Conditions

Heterogeneous Reaction of Nitric Acid with Nitric Oxide on Glass Surfaces under Simulated Atmospheric Conditions

The photolysis of ortho-nitrophenols: a new gas phase source of HONO

Production of hydrogen peroxide enabled by microdroplets

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