Bonding changes during the growth of CdSe nanoparticles in glass

Thermal treatment of Cd and Se doped borosilicate glass yields CdSe nanoparticles that are interesting for applied and fundamental studies of quantum and size effects in semiconductors. Using X-ray absorption spectroscopy at both the Cd and Se K-edges, we have studied the local atomic structure for each of these reactants at several stages of a particle growth. When the doped glass is quenched from 1050 °C, the Cd neighbor is mostly oxygen and the Se neighbor is mostly Zn. With heat treatment at 600–750 °C, the concentration of nearest neighbor Cd–Se bonds increases and becomes dominant while the optical spectrum evolves toward that of a composite containing CdSe.