In this paper we present results of a low-temperature time-resolved photoluminescence (PL) investigation of thin SiO 2 films implanted with silicon ions. In addition to the luminescence of well-known ODCs, some other bands are present in the low-energy region of PL spectra that are attributed to silicon nanoclusters (quantum dots – SiQDs), excitons and hydrogen-related species (HRS). Specific features of SiQD and HRS bands are the nanosecond kinetics and unusual “stepped” PL excitation spectrum in the 3.5–7.5eV range. The possible origin of discovered phenomena is discussed. The obtained results are interpreted taking into account the interference of exciting radiation and dimensional quantization effects.