Time-resolved sensing of chemical species in porous silicon optical microcavity

Time-resolved measurements of red-shifts in the reflectivity spectra of porous silicon multi-layer microcavities, due to exposure to vapor of chemical species, give deep insight about the spatial concentration of the liquid condensed into the pores. Results clearly indicate that capillary condensation starts immediately and proceeds homogeneously all over the stack, yielding a uniform concentration distribution.