SURFACE-COMPOSITION OF GLASSES - MODIFICATIONS INDUCED BY CHEMICAL AND THERMAL TREATMENTS

XPS investigations together with Ar ion depth profiling have been applied to follow compositional as well as structural changes of the outermost layers of soda glass surfaces. Untreated samples and samples treated in 5 mol l** minus **1 HCl at 420 K and dried at 300 K or dehydrated at 550 K were studied. It was found that all the elements, even the structure-forming Al can be removed from the surface (approx. 3 nm) by HCl, leaving behind only Si and O. Reappearance of Al and Na ions on the surface in the dehydration step is demonstrated. Samples silylated by HMDS were tested and a surface model was proposed and verified by quantitative data. These results may help to elucidate problems concerning the preparation of an 'inert' glass surface for application in chromatographic glass capillary columns.