X-RAY PHOTOELECTRON-SPECTROSCOPY OF ALKAL I SILICATE-GLASSES

X-ray photoelectron spectra were measured on the fresh surfaces of sil ica, binary alkali silicate and mixed alkali silicate glasses fracture d in ultra-high vacuum by irradiating with focusing monochromatic Al K alpha X-ray. Binding energies and chemical shifts of Ols, Si2p, Li1s, Na1s, K2p, Rb3d(5/2) and Cs4d(5/2) have been investigated, and charge densities of oxide, silicon and other alkali ions have been discussed . For xNa(2)O .(100-x)SiO2 glasses, electron densities of bridging oxi de ion (BO), non-bridging oxide ion (NBO) and sodium ions increased wi th increasing the Na2O content, suggesting that the bond order between O2p and Na3s (or 3p) increased with increasing the Na2O content. In a ddition, the difference in binding energies between BO1s and NBO1s dec reased with increasing Na2O content indicating that electrons were del ocalized considerably in O2p-Si3d pi bonds, For 33.3R(2)O . 66.7SiO(2) (R = Li, Na, K, Rb, Cs) glasses, charge densities of BO increased wit h increasing ionic radius of alkali ions (Li-->Na-->K, Rb-->Cs). The d egree of polarization of BO increased with increasing ionic radius of alkali ions, For 33.3 ((1-y)Li2O . yCs(2)O]. 66.7SiO(2) glasses, O1s p eak of NBO could not been discriminated between the components belongi ng to Si-O-... Li+ and Si-O-... Cs+, Ols chemical shifts of 33.3((1-x) Li2O . xCs(2)O}. 66.7SiO(2) glasses with increasing Cs2O content were similar to the shifts of 33.3R(2)O.66.7SiO(2) glasses with increasing ionic radius of alkali ions. The area-weighed mean values of Ols peaks appeared to have good correlation with an empirical expression of opt ical basicity.