CHARACTERISTIC FEATURES OF SIZE-SELECTIVE PHOTOETCHING OF CDS NANOPARTICLES AS A MEANS OF PREPARATION OF MONODISPERSE PARTICLES

The photocorrosion behavior of CdS nanoparticle colloid containing par ticles ranging from 4 to 10 nm was investigated using two kinds of mon ochromatic light, one of which was prepared by passing light from a Xe lamp through interference filters, and the other was obtained by an A r ion laser. CdS particles were photocorroded to smaller particles unt il irradiated photons were not absorbed anymore; and the CdS particles obtained after the complete photocorrosion by laser light were much s maller than those resulting from the use of monochromatic light of com parable wavelength. The size selective photocorrosion with the Ar ion laser allowed the preparation of much smaller particles than those in the original colloid. It was found that the rate of photocorrosion dec reased when the pH of the colloid was raised, while the fluorescence i ntensity due to bandgap transition increased. The importance of hole t rap sites in the photodissolution of CdS is discussed based on these f indings.