Mesopore diffusion within porous silicon

Abstract

In many applications exploiting mesoporous silicon (PSi), their performance may be controlled by the rate of diffusive propagation of the confined molecules. The pulsed field gradient technique of nuclear magnetic resonance provides the most direct access to molecular diffusion. The different factors determining the diffusivities in PSi are reviewed. In particular, diffusivities in liquid state are shown to be most strongly affected by mesoscale disorder. Atomistic disorder is shown to control surface diffusion in applications in which PSi is brought into contact with gas phases at low vapor pressures. Correlations between the compositions of phases coexisting within the pore space, namely, liquid and gaseous, and liquid and solid ones, respectively, are briefly discussed.