APPLICATIONS OF SURFACE CHARACTERIZATION TECHNIQUES TO GLASSES.

This review has stressed the new level of glass surface characterization that is now possible with recently developed techniques. As with most analytical techniques, there are definite limitations that must be recognized, including a considerable amount of interpretive judgment that must be exercised. The physical information obtained by the technique is some form of ″average″ over the volume of observation. Inhomogeneities along the plane of the surface having a dimensional scale smaller than the area of observation cannot be distinguished, and the potential exists for misinterpretation in terms of a uniform distribution state yielding the same physical response. similar difficulties exist for inhomogeneities normal to the surface if the dimensional scale is smaller than the depth of observation. Also, the surface interaction inherent in the techniques can perturb the surface and provide misleading results, as in the case of preferential sputtering by ion bombardment. A confident interpretation of characterization information, therefore, is not always possible by application of a single technique, but several techniques applied to the same problem can resolve unccertainties.