scholarly journals The Determination of the Diffusion Coefficient for Thermal Electrons in Water Vapour by the Use of a Modified Blanc's Law Procedure

1986 ◽  
Vol 39 (2) ◽  
pp. 249 ◽  
Author(s):  
Zoran Lj Petrovic
Keyword(s):  
Diffusion Coefficient ◽  
Water Vapour ◽  
Electron Density ◽  
Correction Factor ◽  
Pressure Dependence ◽  
Published Data ◽  
Anomalous Dependence ◽  
Straightforward Application ◽  
Calculated Correction

The Cavalieri electron density technique has been used to measure the diffusion coefficient for thermal electrons in water vapour. When analysed by a straightforward application of Blanc's law to determine the diffusion coefficient for water vapour, the normalized coefficient ND showed an anomalous pressure dependence. The application of a modified procedure, in which these data were corrected using a calculated correction factor, removed the anomalous dependence and gave data which are in agreement with previously published data.

scholarly journals A Novel Time Lag Method for the Analysis of Mixed Gas Diffusion in Polymeric Membranes by On-Line Mass Spectrometry: Pressure Dependence of Transport Parameters

Membranes ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 73 ◽  
Author(s):  
Marcello Monteleone ◽  
Elisa Esposito ◽  
Alessio Fuoco ◽  
Marek Lanč ◽  
Kryštof Pilnáček ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Pressure Dependence ◽  
Diffusion Coefficients ◽  
Gas Diffusion ◽  
Unique Determination ◽  
Mixed Gas ◽  
Polymer Of Intrinsic Microporosity ◽  
On Line ◽  
Intrinsic Microporosity

This paper presents a novel method for transient and steady state mixed gas permeation measurements, using a quadrupole residual gas analyser for the on-line determination of the permeate composition. The on-line analysis provides sufficiently quick response times to follow even fast transient phenomena, enabling the unique determination of the diffusion coefficient of the individual gases in a gas mixture. Following earlier work, the method is further optimised for higher gas pressures, using a thin film composite and a thick dense styrene-butadiene-styrene (SBS) block copolymer membrane. Finally, the method is used to calculate the CO2/CH4 mixed gas diffusion coefficients of the spirobisfluorene-based polymer of intrinsic microporosity, PIM-SBF-1. It is shown that the modest pressure dependence of the PIM-SBF-1 permeability can be ascribed to a much stronger pressure dependence of the diffusion coefficient, which partially compensates the decreasing solubility of CO2 with increasing pressure, typical for the strong sorption behaviour in PIMs. The characteristics of the instrument are discussed and suggestions are given for even more versatile measurements under stepwise increasing pressure conditions. This is the first report on mixed gas diffusion coefficients at different pressures in a polymer of intrinsic microporosity.

scholarly journals Electron Transport Coefficients in Hydrogen and Deuterium

1968 ◽  
Vol 21 (1) ◽  
pp. 43 ◽  
Author(s):  
RW Crompton ◽  
MT Elford ◽  
AI McIntosh
Keyword(s):  
Diffusion Coefficient ◽  
Low Temperature ◽  
Cross Sections ◽  
Room Temperature ◽  
Transport Coefficients ◽  
Low Energy ◽  
Published Data ◽  
Low Energy Electrons ◽  
Electron Transport Coefficients

Measurements have been made of the drift velocity W and the ratio of diffusion coefficient to mobility D/μ for low energy electrons in deuterium at 77�K, and of D/μ in hydrogen at 77 and 293�K. Tabulated data are given for D/μ within the range 2 x 10−20 ≤ E/N ≤ 1.2 x 10−16 V cm2 and for W within the range 8 x 10−20 ≤ E/N ≤ 9.5 x 10−17 V cm2. The low temperature results show a considerably reduced scatter when oompared with previously published data and are of an aocuracy comparable with the results of recent measurements made at room temperature. The data obtained complement those of Lowke and of McIntosh thus completing a set from which a more acourate determination of low energy elastic and inelastic cross sections can be made.

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