Reversible photoluminescence quenching of CdSe/ZnS quantum dots embedded in porous glass by ammonia vapor.

The photoluminescence response of semiconductor CdSe/ZnS quantum dots embedded in a borosilicate porous glass matrix to exposure to ammonia vapor is investigated. The formation of surface complexes on the quantum dots results in quenching of the photoluminescence and a shortening of the luminescence decay time. The process is reversible, desorption of ammonia molecules from the quantum dot surface causes the photoluminescence to recover. The sensitivity of the quantum dot luminescence intensity and decay time to the interaction time and the reversibility of the photoluminescence changes make the CdSe/ZnS quantum dots in porous glass system a candidate for use as an optical sensor of ammonia.

Track membranes with embedded semiconductor nanocrystals: structural and optical examinations.

We studied the optical properties of poly(ethylene terephthalate) ion track membranes of 1.5, 0.5 and 0.05 µm pores impregnated with luminescent semiconductor CdSe/ZnS nanocrystals of different diameters (2.5 and 5 nm). The nanocrystals were embedded from their colloidal solutions in toluene by the immersion of a membrane in a colloidal solution. Localization of quasi-isolated weakly interacting CdSe/ZnS nanocrystals in a loosened layer on the track pore wall surface along with the existence of empty pores was demonstrated. We observed also the spatial separation of nanocrystals of 2.5 and 5 nm in size along the 50 nm pores.