Cadmium clusters in CdI2 layered crystals:: the influence on the optical properties

The influence of overstoichiometric Cd-i atoms on the optical properties of cadmium iodide layered crystals has been investigated. The results of optical absorption, luminescence, and luminescence excitation studies of CdI2 crystals with controlled deviation from stoichiometric composition allow observing correlations between the Cdi concentration and features in absorption and emission spectra up to concentrations of 10(18) cm(-3). At higher concentrations the overstoichiometric cadmium atoms form clusters, which were observed using scanning electron microscopy. The extinction spectra of ( CdIi) (n) clusters are calculated in the frame of Mie theory and are found to correlate with the optical studies.