Effect of gamma-ray irradiation on the size and properties of CdS quantum dots in reverse micelles

Cadmium sulfide quantum dots 1.3-5.6 nm in size have been synthesized in sodium bis(2-ethylhexyl) sulfosuccinate (AOT)-water-isooctane micellar solutions with various [H2O]/[AOT] molar ratios (w=2.5, 5.0 or 10). Gamma irradiation method has been used to change the size and optical properties of quantum dots. It has been found that gamma-irradiation reduces the size polydispersity of quantum dots in the micellar system and alters their fluorescent properties. Fluorescence intensity is enhanced after gamma-irradiation. The average fluorescence lifetime of single quantum dots sized 5.2 +/- 0.4 nm increases from 5.14 to 6.39 ns after gamma-irradiation at a dose of 7.9 kGy. To the best of our knowledge, this is the first report on fluorescence lifetime of single CdS quantum dots in micellar solution. (C) 2013 Elsevier Ltd. All rights reserved.