Preparation and characterization of water-soluble US nanocrystals by surface modification of ethylene diamine

The water-soluble US nanoparticles were obtained by hydrogen bond between the cadmium-thiolate complex on the surface of CdS nanoparticles and ethylene diamine (anhydrous). The modified US nanoparticles enhanced its solubility in H2O and alcohol, The ethylene diamine-capped US nanoparticles were characterized by Fourier Transforrn Infrared Spectroscopy (FTIR), photoluminescence (PL) and Ultraviolet-Visible absorption spectrum (UV-Vis spectrum). The absorption peak at 262 nm was observed, which belonged to ethylene diamine-modificated Cd-thiolate complex at the surface of as-grown US nanoparticles. The results of the PL spectra indicated that the modification of CdS nanoparticles reduced effectively the local surface-trap states. Based on the above results, a possible mechanism for the formation of the water-soluble US nanoparticles was discussed (C) 2004 Elsevier B.V. All rights reserved.