Pore opening effects and transport diffusion in the Knudsen regime in comparison to self- (or tracer-) diffusionS. Zschiegner1, 2, S. Russ1, A. Bunde1 and J. Kärger2
1 Universität Giessen, Institut für Theoretische Physik III - Giessen, Germany
2 Universität Leipzig, Fakultät für Physik und Geowissenschaften - Leipzig, Germany
received 13 December 2006; accepted in final form 23 February 2007; published April 2007
published online 22 March 2007
We study molecular diffusion in linear nanopores with different types of roughness in the so-called Knudsen regime. Knudsen diffusion represents the limiting case of molecular diffusion in pores, where mutual encounters of the molecules within the free pore space may be neglected and the time of flight between subsequent collisions with the pore walls significantly exceeds the interaction time between the pore wall and the molecules. We present an extension of a commonly used procedure to calculate transport diffusion coefficients. Our results show that using this extension, the coefficients of self- and transport diffusion in the Knudsen regime are equal for all regarded systems, which improves previous literature data.
05.40.Fb - Random walks and Levy flights.
66.30.Pa - Diffusion in nanoscale solids.
82.56.Lz - Diffusion.
© Europhysics Letters Association 2007