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Chemical Geology. 01/2012; 332:74-91.
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ABSTRACT: Absorption cross-sections for HNO3 have been measured in the wavelength region 220–340 nm, using a dual-beam diode array spectrometer, with a spectral resolution of 0.3 nm. The results at room temperature were in good agreement with earlier measurements. Absorption over most of the wavelength range showed a distinct temperature dependence, with a decline in cross-section with decreasing temperature in the range 295–239 K. The results lead to quite large effects on the calculated photodissociation rate of HNO3 in the lower stratosphere, especially at the low temperatures and high solar zenith angles characteristic of the polar winter and spring.
Berichte der Bunsengesellschaft für physikalische Chemie. 05/2010; 96(3):399 - 404.
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C. E. Kolb, R. A. Cox,
J. P. D. Abbatt,
Ammann M,
E. J. Davis,
D. J. Donaldson,
B. C. Garrett,
George C,
P. T. Griffiths,
D. R. Hanson,
Kulmala M,
McFiggans G,
Pöschl U,
Riipinen I,
M. J. Rossi,
Rudich Y,
P. E. Wagner,
P. M. Winkler,
D. R. Worsnop,
C. D. O’Dowd
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ABSTRACT: A workshop was held in the framework of the ACCENT (Atmospheric Composition Change – a European Network) Joint Research Programme on "Aerosols" and the Programme on "Access to Laboratory Data". The aim of the workshop was to hold "Gordon Conference" type discussion covering accommodation and reactive uptake of water vapour and trace pollutant gases on condensed phase atmospheric materials. The scope was to review and define the current state of knowledge of accommodation coefficients for water vapour on water droplet and ice surfaces, and uptake of trace gas species on a variety of different surfaces characteristic of the atmospheric condensed phase particulate matter and cloud droplets. Twenty-six scientists participated in this meeting through presentations, discussions and the development of a consensus review. In this review we present an analysis of the state of knowledge on the thermal and mass accommodation coefficient for water vapour on aqueous droplets and ice and a survey of current state-of the-art of reactive uptake of trace gases on a range of liquid and solid atmospheric droplets and particles. The review recommends consistent definitions of the various parameters that are needed for quantitative representation of the range of gas/condensed surface kinetic processes important for the atmosphere and identifies topics that require additional research.
Atmospheric Chemistry and Physics Discussions. 01/2010;
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ABSTRACT: This article, the fifth in the ACP journal series, presents data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the heterogeneous processes on surfaces of solid particles present in the atmosphere, for which uptake coefficients and adsorption parameters have been presented on the IUPAC website in 2010. The article consists of an introduction and guide to the evaluation, giving a unifying framework for parameterisation of atmospheric heterogeneous processes. We provide summary sheets containing the recommended uptake parameters for the evaluated processes. Four substantial appendices contain detailed data sheets for each process considered for ice, mineral dust, sulfuric acid hydrate and nitric acid hydrate surfaces, which provide information upon which the recommendations are made.
Atmospheric Chemistry and Physics. 01/2010;
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ABSTRACT: This article, the fourth in the series, presents kinetic and photochemical data sheets evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of organic halogen species, which were last published in 1997, and were updated on the IUPAC website in 2006/07. The article consists of a summary sheet, containing the recommended kinetic parameters for the evaluated reactions, and four appendices containing the data sheets, which provide information upon which the recommendations are made.
Atmospheric Chemistry and Physics. 01/2008;
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ABSTRACT: The heterogeneous chemistry of HOI, ICl and IBr on sea salt and sea salt proxies has been studied at 274 K using two experimental approaches: a wetted wall flow tube coupled to an electron impact mass spectrometer (WWFT-MS) and an aerosol flow tube (AFT) coupled to a differential mobility analyser (DMA) and a chemical ionisation mass spectrometer (CIMS). Uptake of all three title molecules into bulk aqueous halide salt films was rapid and controlled by gas phase diffusion. Uptake of HOI gave rise to gas-phase ICl and IBr, with the latter being the predominant product whenever Br(-) was present. Only partial release of IBr was observed due to high solubility of dihalogens in the film. ICl uptake gave the same yield of IBr as HOI uptake. Uptake of ICl on NaBr aerosol was accommodation limited with alpha = 0.018 +/- 0.004 and gas phase IBr product has a yield of 0.6 +/- 0.3. The results show that HOI can act as a catalyst for activation of bromine from sea-salt aerosols in the marine boundary layer, via the reactions: HOI(aq) + Cl + H--> ICl(aq) + H(2)O(l) and ICl(aq) + Br--> IBr(aq) + Cl.
Physical Chemistry Chemical Physics 07/2007; 9(24):3136-48. · 3.57 Impact Factor
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ABSTRACT: This article, the second in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of Organic species, which were last published in 1999, and were updated on the IUPAC website in late 2002, and subsequently during the preparation of this article. The article consists of a summary table of the recommended rate coefficients, containing the recommended kinetic parameters for the evaluated reactions, and eight appendices containing the data sheets, which provide information upon which the recommendations are made.
Atmospheric Chemistry and Physics. 01/2006;
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ABSTRACT: The phase transitions and hygroscopic growth of two humic acid aerosols (Aldrich sodium salt and Leonardite Standard (IHSS)) and their mixtures with ammonium sulphate have been investigated using a combination of two techniques, Fourier transform infra-red (FTIR) spectroscopy and tandem differential mobility analysis (TDMA). A growth factor of 1.16 at 85% relative humidity ( RH ) was found for the Aldrich humic acid which can be regarded as an upper limit for growth factors of humic-like substances (HULIS) found in atmospheric aerosol and is significantly smaller than that of typical atmospheric inorganics. We find that the humic acid aerosols exhibit water uptake over all relative humidities with no apparent phase changes, suggesting that these aerosols readily form supersaturated droplets. In the mixed particles, the humic acid component decreases the deliquescence relative humidity (DRH) and increases the efflorescence relative humidity (ERH) of the ammonium sulphate component, and there is some degree of water uptake prior to ammonium sulphate deliquescence. In addition, at low RH, the FTIR spectra show that the ammonium is present in a different chemical environment in the mixed aerosols than in crystalline ammonium sulphate, perhaps existing as a complex with the humic materials. The growth factors of the mixed aerosols are intermediate between those of the single-component aerosols and can be predicted assuming that the inorganic and organic fractions take up water independently.
Atmospheric Chemistry and Physics. 01/2006;
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ABSTRACT: Diode laser spectroscopy has been employed to monitor the formation of chlorine nitrate (ClONO2) in the association reaction of ClO with NO2. Chlorine nitrate is the only stable end-product of this reaction at room temperature. Time-resolved measurements of ClONO2 formation using molecular modulation showed no evidence for any involvement of unstable isomers of ClNO3 in the reaction. These measurements gave a value of k1 = (1.8 ± 0.4) × 10−31 cm6/molecule2 · s for the reaction at 295 K and an upper limit of 5 ms for the lifetime of any isomeric products at this temperature.
International Journal of Chemical Kinetics 10/2004; 16(4):445 - 467. · 1.01 Impact Factor
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ABSTRACT: The rate constant for the HO2 self reaction has been determined as a function of methanol vapor concentration at 278 K and 299 K. A molecular modulation technique was used in which HO2 radicals were photochemically produced in flowing gas mixtures comprised of Cl2, CH3OH, N2 and O2 with HO2 monitored in the UV at 220 nm. A positive linear dependence of the second order rate constant on methanol concentration was found and this effect increased with decreasing temperature. The rate constant for the HO2 self reaction can be described by in nitrogen at atmospheric pressure and in the methanol concentration range 1 · 1016 to 3 · 1017 molecules cm−3.
International Journal of Chemical Kinetics 09/2004; 20(4):283 - 295. · 1.01 Impact Factor
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International Journal of Chemical Kinetics 09/2004; 21(2):115 - 150. · 1.01 Impact Factor
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ATMOSPHERIC CHEMISTRY AND PHYSICS 01/2004; 4(6):1461-1738. · 5.52 Impact Factor
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04/2002;
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04/2002;
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04/2002;
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04/2002;
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04/2002;
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ABSTRACT: The use of a tungstic oxide semiconductor as a sensor for ozone at concentration levels relevant to atmospheric monitoring applications is an important advance in attempts to produce cheap, lightweight and reliable instruments. Problems of stability are a possible obstacle to this application. A model that describes the response of these sensors to ozone is proposed here and using it an explanation for the drift of resistance with time at constant concentrations of ozone is given. Consideration of this drift model enables a measurement routine to be employed that compensates for the drift observed experimentally, thus producing a reliable calibration of the sensor.
Measurement Science and Technology 04/2001; 12(6):684. · 1.49 Impact Factor
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F S Rowland,
D R Blake,
B R Larsen,
A Lindskog,
P J Peterson,
W P Williams,
T J Wallington,
M J Pilling,
N Carslaw,
D J Creasey, [......],
F Plana,
B Artiño,
A Rauterberg-Wulff,
G W Israël,
T A Rocha,
A C Duarte,
A Röhrl,
G Spindler,
M R Strommen,
R Berkowicz
Environmental Science and Pollution Research 02/1998; 5(3):119-96. · 2.65 Impact Factor
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ABSTRACT: This paper updates and extends part of the previous data base of critical evaluations of the kinetics and photochemistry of gas-phase chemical reactions of neutral species involved in atmospheric chemistry [J. Phys. Chem. Ref. Data {bold 9}, 295 (1980); {bold 11}, 327 (1982); {bold 13}, 1259 (1984); {bold 18}, 881 (1989); {bold 21}, 1125 (1992); {bold 26}, 521 (1997)]. The present evaluation is limited to the following families of atmospherically important reactions: O{sub x}, HO{sub x}, NO{sub x}, and SO{sub x}. The work has been carried out by the authors under the auspices of the IUPAC Subcommittee on Gas Phase Kinetic Data Evaluation for Atmospheric Chemistry. Data sheets have been prepared for 151 thermal and photochemical reactions, containing summaries of the available experimental data with notes giving details of the experimental procedures. For each thermal reaction, a preferred value of the rate coefficient at 298 K is given together with a temperature dependence where possible. The selection of the preferred value is discussed and estimates of the accuracies of the rate coefficients and temperature coefficients have been made for each reaction. For each photochemical reaction the data sheets list the preferred values of the photoabsorption cross-sections and the quantum yields of the photochemical reactions together with comments on how they were selected. The data sheets are intended to provide the basic physical chemical data needed as input for calculations which model atmospheric chemistry. A table summarizing the preferred rate data is provided, together with an appendix listing the available data on enthalpies of formation of the reactant and product species. {copyright} {ital 1997 American Institute of Physics and American Chemical Society.}
Journal of Physical and Chemical Reference Data 10/1997; 26(6). · 3.17 Impact Factor
