Length and occupancy dependence of the tracer exchange in single-file systems

The tracer exchange between a finite single-file channel (in which the diff using guest particles are not able to pass each other) and its surroundings is considered. A mean-field calculation shows that the mean intracrystalli ne residence time tau(intra) is proportional to the 3rd power of the channe l length L. Further, it is proportional to Theta/(1-Theta), where Theta den otes the relative occupancy. Monte Carlo simulations confirm these results to a satisfactory accuracy, especially at high occupancy. The essential mec hanism of tracer exchange is considered in more detail. (C) 1999 American I nstitute of Physics. [S0021-9606(99)70707-5].