XAFS STUDY OF CDSE QUANTUM DOTS IN A SILICATE GLASS

X-ray absorption fine structure (XAFS) spectroscopy of a zinc potassiu m silicate glass containing small quantities of cadmium (0.5%), seleni um (0.4%) and sulphur (0.1%) and heat treated in various ways has enab led the atomic environments of these elements and also zinc to be trac ed during the development of cadmium chalcogen quantum dots. Both cadm ium-oxygen and cadmium-selenium centres have been identified from cadm ium XAFS. Complementary information on the CdSe phase has been recorde d from selenium XAFS where in addition selenium-selenium contacts poin t to a selenium phase, which is prominent in the as-prepared glass. Kn owing the proportion of CdSe nanocrystallites at each stage has enable d the optical absorption coefficient of the quantum dots to be estimat ed from the optical absorption of the glass.