| Abstract
| - The photoluminescence (PL) at 300 and 90 K from the mesoporous silicas (MSs) [ordered (MCM-41) anddisordered (DMSs)] of variously sized pores induced either by ArF laser light (λexc = 193 nm) or by Nd:YAG (yttrium−aluminum−garnet) laser light (λexc = 266 nm) was studied. The spectra were measured inboth conventional and time-resolved detection modes. It has been shown that PL induced by 266-nm lightresults from a direct one-photon excitation of hydrogen-related species (the green band) situated on the internalpore surfaces and nonbridging oxygen hole centers (NBOHCs, the red bands) located both on the surface andinside ∼1-nm sized bulk fragments (pore walls). Alternatively, an indirect excitation of the light emitters dueto the energy transfer through two-photon-produced free excitons (FEs) is responsible for PL in the case of193-nm excitation. In addition, the self-trapping of FEs followed by radiative relaxation results in the blueband, which can only be induced by 193-nm light. The PL properties of MSs in comparison with those ofsilica nanoparticles and bulk silica are discussed.
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