Synthesis and characterization of colloidal nanocrystals of capped gallium arsenide

We have recently reported [Chem. Mater. 6, 2056 (1994)] the metathetical reaction of GaCl3 dissolved in chelating organic solvents with (Na/K)(3)As in aromatic solvents to synthesize multigram quantities of GaAs nanocrystals. The extraction of the as-synthesized nanocrystals with methanol resulted in surface derivatization of the nanoparticles in which methanol capped GaAs quantum dots were obtained. The surface bound methanol facilitates the formation of colloidal suspensions of GaAs. These suspensions have been stable for more than eighteen months despite repeated exposures to atmosphere and light. The average particle size of the colloidal GaAs obtained by evaporating the methanol solvent was approximately 5 nm. The capped GaAs nanocrystals have been characterized by XRD, XPS, NMR, FT-IR PAS, HRTEM, elemental analysis and UV-Vis spectroscopy.