DIFFUSION WITH MULTIPLE KINDS OF TRAPPING SITES

Since diffusion in solid is influenced by trapping sites which have di fferent binding energies, analytic solutions to describe diffusion wit h multiple kinds of trapping sites have been derived for dilute system s without using the assumption of local equilibrium. Numerical compari sons with the local equilibrium treatment show that the transport of f ree atoms evaluated by the present solutions is faster at short times than that of the local equilibrium treatment. As time passes, the diff erence becomes small. The present solutions also show that the transpo rt of free atoms is influenced by the initial concentrations at trappi ng sites, and that the apparent transport is accelerated in some cases . Using the present solutions, systematic investigations of diffusion phenomena with many kinds of trapping sites become possible. (C) 1998 American Institute of Physics.