The mechanism of singlet oxygen generation on the surface of excited nanoporous silicon

The mechanism of singlet-oxygen generation on the surface of photoexcited nanoporous silicon has been theoretically analyzed. It is shown that the mechanism of singlet-oxygen generation is based on nonradiative energy transfer from nanoporous silicon to an oxygen molecule according to the Dexter exchange mechanism. An analytical expression is obtained, and the probability of energy transfer from nanoporous silicon to an oxygen molecule is numerically estimated. It is shown that its numerical value, on the order of $\sim$(10$^{3}$–10$^{4}$) s$^{-1}$, is in good agreement with the experimental data.