XPS STUDY OF LEACHED GLASS SURFACES

By use of a special deconvolution algorithm, it was possible to decompose the XPS O 1s signal into several components reflecting different oxygen bonds. The influence of exposure in vacuo, environmental atmosphere, distilled water, and in a polish solution as corrosive media on the surface of different glasses has been studied. The O 1s signals of fused silica, Na2O·nSiO2 glasses, a BaO·SiO2 and a BaOB2O3SiO2 glass (Schott SK 16) were analyzed. On the glass surfaces, leached layers were formed and analyzed qualitatively and semiquantitatively by XPS and optical and infrared methods. As a reference, virgin surfaces of samples broken in ultrahigh vacuum have been used. The absolute binding energies as well as the shifts relative to the bridging oxygen in ≡SiOSi≡ have been determined for the first for silanol groups ≡SiOH in the surface layer (532.9±0.2 eV and 0.56±0.10 eV, respectively) and for water and/or hydronium bound oxygen (533.6±0.2eV and 1.25±0.10 eV, respectively). Silanol groups are formed in atmosphere as well as by the residual gas in vacuo. Details of the growth of the leached layer were studied, e.g. the dissolution of Ba++ ions and the growth of the thickness of the leached layer. © 1990.