RADIATION EFFECTS ON LEAD SILICATE GLASS SURFACES

Radiation-induced changes in the microstructure of lead silicate glass were investigated in situ under Mg K-alpha irradiation in an ultra-hi gh vacuum (UHV) environment by X-ray photoelectron spectroscopy (XPS). Lead-oxygen bond breaking resulting in the formation of pure lead was observed. The segregation, growth kinetics and the structural relaxat ion of the lead, with corresponding changes in the oxygen and silicon on the glass surfaces were studied by measuring the time-dependent cha nges in concentration, binding energy shifts, and the full width at ha lf maximum. A bimodal distribution of the oxygen XPS signal, caused by bridging and non-bridging oxygens, was found during the relaxation pr ocess. All experimental data indicate a reduction of the oxygen concen tration, a phase separation of the lead from the glass matrix, and the metallization of the lead occurred during and after the X-ray irradia tion.