2010 Volume 78 Issue 2 Pages 170-174
Effects of reaction conditions on size-selective photoetching of CdTe nanocrystals were presented focusing on electron mediator and wavelength of irradiating light. Methyl viologen, which was expected to work as an electron mediator of photo-induced oxygen reduction accelerating the photoetching, decreased significantly the rate of the reaction. The results are compared with the photoetching of CdS nanocrystals in terms of overpotential for oxygen reduction and adsorption of electron mediators on nanocrystals. Under optimized conditions, the photoetching can produce highly monodispersed nanocrystals having fluorescence peak of fwhm value as small as 23.5 nm around the wavelength region where CdTe nanocrystals are stably produced by the conventional synthesis. However, further blue shifts of irradiating light gradually increased the fluorescence fwhm value, and the exciton peaks became unclear as well. The results were considered by comparing with recently reported magic-sized nanoclusters.