Fluorescence spectra of the cross-section of a PSi layer of sample II(Em/Ag/H
O). Espectra are recorded on a point situated at 3 μm from Si-PSi interface. (a) After 30 days preparation, and (b) freshly prepared. Pore size is 60 nm. The Raman band of PSi at 503 cm−1 is marked with an asterisk.