ИСТИНА

Photoluminescence (PL) transients of porous silicon (PSi) nanoparticles in different ambients under interaction with oxygen molecules, which resulted in the photosensitized generation of singlet oxygen (SO), are experimentally and theoretically investigated in a time scale from hundreds of nanoseconds to tens of minutes after the photoexcitation beginning. The “visible” PL band undergoes a quenching due to the energy transfer from excitons in PSi to nonradiative centers (defects) and oxygen molecules adsorbed on the internal surface of PSi. The PL transients for excitons and radiative emission from the defect states and SO molecules exhibit power low dependences versus the photoexcitation time. This effect is explained by a model of rate equations in a coupled system of the interacting excitons, defects and oxygen molecules. Luminescence transients of SO photosensitized by PSi nanoparticles dispersed in heavy water were measured and explained by using the proposed model.