A facile “green” synthesis of ascorbic acid-capped ZnSe nanoparticles

A simple, green room temperature synthesis of ascorbic acid-capped ZnSe nanoparticles is hereby reported. By varying the pH of the solution, the temporal evolution of the optical properties and shape of the nanocrystals was investigated. The nanoparticles were characterized by UV–vis absorption and photoluminescence spectroscopy (PL), transmission electron microscope (TEM) and infra-red spectroscopy (IR). All the particles exhibited quantum confinement in their optical spectra. An atypical optical spectrum was observed at pH 11 after 5 h attributed to digestive ripening and shrinkage of ZnSe core. From the TEM image we inferred that the reaction is kinetically driven at pH 7 producing elongated particles as the reaction times increases, while spherical particles are produced at pH 4 and 11. The IR spectroscopy confirmed the capping of ascorbic acid and its deprotonation to give ascorbate ions.