Diffusion and capillary flow in track-etched membranes

Nitrogen transport at 77 K through the cylindrical pores in 0.01 μm track-etched membranes occurs by a combination of Knudsen diffusion and capillary flow. This transport can be quantitatively predicted without adjustable parameters from a modified form of the theory of Abeles et al. (1991). This implies that some anomalies previously observed for transport with capillary condensation are geometrical artifacts of the heterogeneous pores which were used.