STUDY OF MOLECULAR-SURFACE DIFFUSION BY IMAGING STATIC SECONDARY-ION MASS-SPECTROMETRY (SIMS) - POLYMERS ON AG-SURFACES

A new technique for the investigation of surface diffusion is describe d. The method is based upon imaging static SIMS. Provided a well-defin ed boundary between a covered and an uncovered surface area can be pro duced by an appropriate procedure, this technique can be applied to an y substrate-overlayer combination, including involatile molecular laye rs, as well as isotopically labelled elemental or molecular layers. We applied this technique to study the surface diffusion of polystyrene (PS), polydimethylsiloxane (PDMS), polymethylmethacrylate (PMMA), and the perfluorinated polyether Krytox on etched Ag-substrates at room te mperature. For PDMS and Krytox, we found a considerable surface diffus ion with diffusion coefficients in the range of 10(-7)-10(-6) cm(2)/s. In contrast, for PMMA and PS, no surface diffusion was observed at ro om temperature. (C) 1998 Elsevier Science B.V. All rights reserved.