One of the great challenges of nanotechnology is how to produce and modify objects at nanoscale dimensions. The search for physical and chemical methods for controlled synthesis, modification and characterization of semiconductor nanocrystals is of special interest due to their novel electronic and optical properties. Recently we have achieved the first laser-induced phase transformation in semiconductor nanocrystals , irradiating colloidal solutions of CdS nanocrystals with 7 ns pulses of 532 nm wavelength. We used established wet-chemistry methods to synthesize the CdS nanocrystals, and a combination of electron microscopy methods to determine the structure, size and composition of the nanocrystals. In the present paper we report a wavelength dependence of the laser-induced phase transformations in CdS. We also explore electron-induced transformations in comparison with their photon counterparts.
Aqueous colloidal solutions of CdS nanocrystals were prepared by mixing of CdCl2 with Na2S in the presence of Sodium Mercaptoacetate and HC1 .