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Isotope effect in Knudsen diffusion 


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The isotope effect in Knudsen diffusion has been studied in several papers. Joshi et al. developed a predictive model incorporating the Z-potential approach and found that the Knudsen effect on mass transfer between a plasma gas and a small particle is significant and depends on particle size, surface conditions, and temperatures of the plasma and particle surface . Kluge and Schober used molecular-dynamics simulation to calculate the diffusional isotope effect in a monatomic Lennard-Jones liquid and observed a reduction of the isotope effect with decreasing temperature and changing density, indicating an increase in the collectivity of motion . Glyde derived a clear expression for the mass dependence of the frequency factor in tracer diffusion and found that it depends explicitly on the mass of the surrounding host atoms, with a reduced contribution for light tracer atoms and an increased contribution for heavy tracer atoms . Seleznev and Suetin calculated the magnitude of the diffusion baroeffect in a capillary and demonstrated agreement with experimental results, as well as the Onsager reciprocal relation . Whillans et al. did not provide specific information on the isotope effect in their abstract .

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Open accessJournal ArticleDOI
I. M. Whillans, H. Clausen, P. Grootes 
The provided paper does not mention the isotope effect in Knudsen diffusion.
The provided paper does not mention anything about the isotope effect in Knudsen diffusion.
Journal ArticleDOI
15 Apr 1969-Physical Review
9 Citations
The provided paper does not mention anything about Knudsen diffusion or the isotope effect in Knudsen diffusion.
The provided paper does not mention anything about the isotope effect in Knudsen diffusion.
Open accessJournal ArticleDOI
M. Kluge, H. R. Schober 
01 Jul 2000-Physical Review E
15 Citations
The provided paper does not discuss the isotope effect in Knudsen diffusion.

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Isotope effect in diffusion5 answersIsotope effects in diffusion refer to the influence of isotopic substitution on the rate of diffusion. The classical-quantum crossover temperature and quantum tunneling rate lose their mass dependence due to the nonadiabatic effect of the heat bath. The frequency factor in the classical jump rate for tracer diffusion depends explicitly on the mass of the surrounding host atoms, resulting in reduced or increased contributions for light or heavy tracer atoms, respectively. Isotope mass effects have been applied to the study of defects and diffusion in nonstoichiometric metal oxides. Molecular dynamics simulations of a binary Lennard Jones liquid show a strong reduction of the diffusional isotope effect with decreasing temperature, indicating an increase in the collectivity of motion. Measurements of the isotope effect for diffusion in pure single crystals of silver and copper show a value significantly less than unity, suggesting the involvement of correlation factors and the fraction of kinetic energy associated with tracer-vacancy exchange.
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