"Green" and controlled synthesis of single family "magic-size" cadmium selenide nanocrystals by the use of cyclo-hexeno-1,2,3-selenadiazole an organoselenium compound

Single family "magic-size" CdSe nanocrystals (MSNCs) have been obtained by reasonably low temperature thermolysis of cyclo-hexeno-1,2,3-selenadiazole i.e. an organoselenium precursor. The reaction of selenium precursor with metal salt at temperatures between 100 and 150 degrees C leads to formation of stabilized magic-size nano-clusters showing sharp and persistent absorption peaks at 371 nm and 392 nm. The present approach is without the use of generally employed 'toxic' reagents thus making the method virtually green. The photoluminescence (PL) emission spectrum shows two features first a band-gap emission at 405 nm and second a broad-band emission from similar to 430 to 680 nm. The X-ray diffraction (XRD) measurements indicate the formation of zinc-blende (cubic) crystal structure. The detailed characterization by X-ray photoelectron spectroscopy (XPS), Energy dispersion X-ray analysis (EDX), Transmission electron microscopy (TEM), Selected area electron diffraction (SAED) and Infrared spectroscopy (IR) is described.