scholarly journals Compilation and evaluation of gas phase diffusion coefficients of reactive trace gases in the atmosphere: volume 1. Inorganic compounds

2014 ◽  
Vol 14 (17) ◽  
pp. 9233-9247 ◽  
Author(s):  
M. J. Tang ◽  
R. A. Cox ◽  
M. Kalberer
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Diffusion Coefficients ◽  
Inorganic Compounds ◽  
Trace Gases ◽  
Empirical Method ◽  
Phase Diffusion ◽  
Reactive Trace Gases ◽  
Pressure Independent ◽  
Semi Empirical

Abstract. Diffusion of gas molecules to the surface is the first step for all gas–surface reactions. Gas phase diffusion can influence and sometimes even limit the overall rates of these reactions; however, there is no database of the gas phase diffusion coefficients of atmospheric reactive trace gases. Here we compile and evaluate, for the first time, the diffusivities (pressure-independent diffusion coefficients) of atmospheric inorganic reactive trace gases reported in the literature. The measured diffusivities are then compared with estimated values using a semi-empirical method developed by Fuller et al. (1966). The diffusivities estimated using Fuller's method are typically found to be in good agreement with the measured values within ±30%, and therefore Fuller's method can be used to estimate the diffusivities of trace gases for which experimental data are not available. The two experimental methods used in the atmospheric chemistry community to measure the gas phase diffusion coefficients are also discussed. A different version of this compilation/evaluation, which will be updated when new data become available, is uploaded online (https://sites.google.com/site/mingjintang/home/diffusion).

scholarly journals Compilation and evaluation of gas-phase diffusion coefficients of inorganic reactive trace gases in the atmosphere

2014 ◽  
Vol 14 (10) ◽  
pp. 15645-15682 ◽  
Author(s):  
M. J. Tang ◽  
R. A. Cox ◽  
M. Kalberer
Keyword(s):  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Diffusion Coefficients ◽  
Trace Gases ◽  
Empirical Method ◽  
Phase Diffusion ◽  
Reactive Trace Gases ◽  
Pressure Independent ◽  
Semi Empirical ◽  
First Time

Abstract. Diffusion of gas molecules to the surface is the first step for all gas-surface reactions. Gas phase diffusion can influence and sometimes even limit the overall rates of these reactions; however, there is no database of the gas phase diffusion coefficients of atmospheric reactive trace gases. Here we compile and evaluate, for the first time, the diffusivities (pressure-independent diffusion coefficients) of atmospheric inorganic reactive trace gases reported in the literature. The measured diffusivities are then compared with estimated values using a semi-empirical method developed by Fuller et al. (1966). The diffusivities estimated using Fuller's method are typically found to be in good agreement with the measured values within ±30%, and therefore Fuller's method can be used to estimate the diffusivities of trace gases for which experimental data are not available. The two experimental methods used in the atmospheric chemistry community to measure the gas phase diffusion coefficients are also discussed.

scholarly journals Compilation and evaluation of gas phase diffusion coefficients of halogenated organic compounds

2018 ◽  
Vol 5 (7) ◽  
pp. 171936 ◽  
Author(s):  
Wenjun Gu ◽  
Peng Cheng ◽  
Mingjin Tang
Keyword(s):  
Gas Phase ◽  
Diffusion Coefficients ◽  
Input Parameter ◽  
Empirical Method ◽  
Trace Gas ◽  
Temperature And Pressure ◽  
Organic Halogens ◽  
Semi Empirical ◽  
Method Show ◽  
Good Agreement

Organic halogens are of great environmental and climatic concern. In this work, we have compiled their gas phase diffusivities (pressure-normalized diffusion coefficients) in a variety of bath gases experimentally measured by previous studies. It is found that diffusivities estimated using Fuller's semi-empirical method agree very well with measured values for organic halogens. In addition, we find that at a given temperature and pressure, different molecules exhibit very similar mean free paths in the same bath gas, and then propose a method to estimate mean free paths in different bath gases. For example, the pressure-normalized mean free paths are estimated to be 90, 350, 90, 80, 120 nm atm in air (and N 2 /O 2 ), He, argon, CO 2 and CH 4 , respectively, with estimated errors of around ±25%. A generic method, which requires less input parameter than Fuller's method, is proposed to calculate gas phase diffusivities. We find that gas phase diffusivities in He (and air as well) calculated using our method show fairly good agreement with those measured experimentally and estimated using Fuller's method. Our method is particularly useful for the estimation of gas phase diffusivities when the trace gas contains atoms whose diffusion volumes are not known.

scholarly journals Technical note: Determination of binary gas-phase diffusion coefficients of unstable and adsorbing atmospheric trace gases at low temperature – arrested flow and twin tube method

2020 ◽  
Vol 20 (6) ◽  
pp. 3669-3682 ◽  
Author(s):  
Stefan Langenberg ◽  
Torsten Carstens ◽  
Dirk Hupperich ◽  
Silke Schweighoefer ◽  
Ulrich Schurath
Keyword(s):  
Gas Phase ◽  
Diffusion Coefficients ◽  
Trace Gases ◽  
Heterogeneous Reactions ◽  
Viscosity Data ◽  
Atmospheric Conditions ◽  
Binary Diffusion ◽  
Phase Diffusion ◽  
Flow Method ◽  
Binary Diffusion Coefficients

Abstract. Gas-phase diffusion is the first step for all heterogeneous reactions under atmospheric conditions. Knowledge of binary diffusion coefficients is important for the interpretation of laboratory studies regarding heterogeneous trace gas uptake and reactions. Only for stable, nonreactive and nonpolar gases do well-established models for the estimation of diffusion coefficients from viscosity data exist. Therefore, we have used two complementary methods for the measurement of binary diffusion coefficients in the temperature range of 200 to 300 K: the arrested flow method is best suited for unstable gases, and the twin tube method is best suited for stable but adsorbing trace gases. Both methods were validated by the measurement of the diffusion coefficients of methane and ethane in helium and air as well as nitric oxide in helium. Using the arrested flow method the diffusion coefficients of ozone in air, dinitrogen pentoxide and chlorine nitrate in helium, and nitrogen were measured. The twin tube method was used for the measurement of the diffusion coefficient of nitrogen dioxide and dinitrogen tetroxide in helium and nitrogen.

scholarly journals Compilation and evaluation of gas-phase diffusion coefficients of reactive trace gases in the atmosphere: volume 2. Organic compounds and Knudsen numbers for gas uptake calculations

2015 ◽  
Vol 15 (4) ◽  
pp. 5461-5492 ◽  
Author(s):  
M. J. Tang ◽  
M. Shiraiwa ◽  
U. Pöschl ◽  
R. A. Cox ◽  
M. Kalberer
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Diffusion Coefficients ◽  
Inorganic Compounds ◽  
Measurement Data ◽  
Gas Uptake ◽  
Phase Diffusion ◽  
Knudsen Numbers ◽  
Wide Range ◽  
Cloud Particles

Abstract. Diffusion of organic vapours to the surface of aerosol or cloud particles is an important step for the formation and transformation of atmospheric particles. So far, however, a database of gas phase diffusion coefficients for organic compounds of atmospheric interest has not been available. In this work we have compiled and evaluated gas phase diffusivities (pressure-independent diffusion coefficients) of organic compounds reported by previous experimental studies, and we compare the measurement data to estimates obtained with Fuller's semi-empirical method. The difference between measured and estimated diffusivities are mostly < 10%. With regard to gas-particle interactions, different gas molecules, including both organic and inorganic compounds, exhibit similar Knudsen numbers (Kn) although their gas phase diffusivities may vary over a wide range. Knudsen numbers of gases with unknown diffusivity can be approximated by a simple function of particle diameter and pressure and can be used to characterize the influence of diffusion on gas uptake by aerosol or cloud particles. We use a kinetic multi-layer model of gas-particle interaction to illustrate the effects of gas phase diffusion on the condensation of organic compounds with different volatilities. The results show that gas-phase diffusion can play a major role in determining the growth of secondary organic aerosol particles by condensation of low-volatility organic vapours.

scholarly journals Compilation and evaluation of gas phase diffusion coefficients of reactive trace gases in the atmosphere: Volume 2. Diffusivities of organic compounds, pressure-normalised mean free paths, and average Knudsen numbers for gas uptake calculations

2015 ◽  
Vol 15 (10) ◽  
pp. 5585-5598 ◽  
Author(s):  
M. J. Tang ◽  
M. Shiraiwa ◽  
U. Pöschl ◽  
R. A. Cox ◽  
M. Kalberer
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Diffusion Coefficients ◽  
Inorganic Compounds ◽  
Measurement Data ◽  
Phase Diffusion ◽  
Knudsen Numbers ◽  
Wide Range ◽  
Gas Molecules ◽  
Cloud Particles

Abstract. Diffusion of organic vapours to the surface of aerosol or cloud particles is an important step for the formation and transformation of atmospheric particles. So far, however, a database of gas phase diffusion coefficients for organic compounds of atmospheric interest has not been available. In this work we have compiled and evaluated gas phase diffusivities (pressure-independent diffusion coefficients) of organic compounds reported by previous experimental studies, and we compare the measurement data to estimates obtained with Fuller's semi-empirical method. The difference between measured and estimated diffusivities are mostly < 10%. With regard to gas-particle interactions, different gas molecules, including both organic and inorganic compounds, exhibit similar Knudsen numbers (Kn) although their gas phase diffusivities may vary over a wide range. This is because different trace gas molecules have similar mean free paths in air at a given pressure. Thus, we introduce the pressure-normalised mean free path, λP ≈ 100 nm atm, as a near-constant generic parameter that can be used for approximate calculation of Knudsen numbers as a simple function of gas pressure and particle diameter to characterise the influence of gas phase diffusion on the uptake of gases by aerosol or cloud particles. We use a kinetic multilayer model of gas-particle interaction to illustrate the effects of gas phase diffusion on the condensation of organic compounds with different volatilities. The results show that gas phase diffusion can play a major role in determining the growth of secondary organic aerosol particles by condensation of low-volatility organic vapours.

scholarly journals Technical note: Determination of binary gas phase diffusion coefficients of unstable and adsorbing atmospheric trace gases at low temperature – Arrested Flow and Twin Tube method

2019 ◽  
Author(s):  
Stefan Langenberg ◽  
Torsten Carstens ◽  
Dirk Hupperich ◽  
Silke Schweighoefer ◽  
Ulrich Schurath
Keyword(s):  
Gas Phase ◽  
Diffusion Coefficients ◽  
Trace Gases ◽  
Heterogeneous Reactions ◽  
Viscosity Data ◽  
Atmospheric Conditions ◽  
Binary Diffusion ◽  
Phase Diffusion ◽  
Flow Method ◽  
Binary Diffusion Coefficients

Abstract. Gas phase diffusion is the first step for all heterogeneous reactions under atmospheric conditions. Knowledge of binary diffusion coefficients is important for the interpretation of laboratory studies regarding heterogeneous trace gas uptake and reactions. Only for stable, nonreactive and non polar gases well-established models for the estimation of diffusion coefficients from viscosity data do exist. Therefore, we have used two complementary methods for the measurement of binary diffusion coefficients in the temperature range of 200 K to 300 K: the arrested flow method is best suited for unstable gases and the twin tube method is best suited for stable but adsorbing trace gases. Both methods were validated by measurement of diffusion coefficients of methane and ethane in helium and air and nitric oxide in helium. Using the arrested flow method the diffusion coefficients of ozone in air, dinitrogen pentoxide and chlorine nitrate in helium and nitrogen were measured. The twin tube method was used for the measurement of the diffusion coefficient of nitrogen dioxide and dinitrogen tetroxide in helium and nitrogen.

On the trustability of semi-empirical methods to the calculation of gas phase formation enthalpies of inorganic compounds containing heavy metals: tin borates

2017 ◽  
Author(s):  
Robson de Farias
Keyword(s):  
Heavy Metals ◽  
Gas Phase ◽  
Phase Formation ◽  
Inorganic Compounds ◽  
Formation Enthalpy ◽  
Computational Time ◽  
Gas Formation ◽  
Formation Enthalpies ◽  
Knudsen Effusion Mass Spectrometry ◽  
Semi Empirical

<p>In the present work, are calculated the gas formation enthalpies (SE; PM3 and PM6) for tin borates: SnB<sub>2</sub>O<sub>4</sub><sup> </sup>and Sn<sub>2</sub>B<sub>2</sub>O<sub>5</sub>. The calculated values are compared with experimental ones, obtained by Knudsen effusion mass spectrometry [3]. It is shown that SE methods, besides their lower computational time consuming can, indeed, provide reliable gas phase formation enthalpy values for inorganic compounds containing heavy metals.</p>

scholarly journals Modelling atmospheric OH-reactivity in a boreal forest ecosystem

2011 ◽  
Vol 11 (18) ◽  
pp. 9709-9719 ◽  
Author(s):  
D. Mogensen ◽  
S. Smolander ◽  
A. Sogachev ◽  
L. Zhou ◽  
V. Sinha ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Transport Model ◽  
Inorganic Compounds ◽  
Chemistry Transport Model ◽  
One Dimensional ◽  
Inorganic Species ◽  
Individual Contributions ◽  
The Individual

Abstract. We have modelled the total atmospheric OH-reactivity in a boreal forest and investigated the individual contributions from gas phase inorganic species, isoprene, monoterpenes, and methane along with other important VOCs. Daily and seasonal variation in OH-reactivity for the year 2008 was examined as well as the vertical OH-reactivity profile. We have used SOSA; a one dimensional vertical chemistry-transport model (Boy et al., 2011a) together with measurements from Hyytiälä, SMEAR II station, Southern Finland, conducted in August 2008. Model simulations only account for ~30–50% of the total measured OH sink, and in our opinion, the reason for missing OH-reactivity is due to unmeasured unknown BVOCs, and limitations in our knowledge of atmospheric chemistry including uncertainties in rate constants. Furthermore, we found that the OH-reactivity correlates with both organic and inorganic compounds and increases during summer. The summertime canopy level OH-reactivity peaks during night and the vertical OH-reactivity decreases with height.

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