INFLUENCE OF SURFACE RELAXATIONS ON X-RAY-INTENSITIES OF MICROCRYSTALS

The influence of surface relaxations on the intensity of microcrystals was investigated. Since the volume fraction of near surface atoms bec omes appreciable for submicrometer crystals, it is important to estima te whether observed intensities of submicrometer crystals can be inter preted with standard structure refinement methods or whether surface r elaxations produce a significant deviation from the intensities of the perfect crystal. Structure simulation techniques were applied in orde r to calculate the intensity of microcrystals of various sizes. Differ ent models of surface relaxations were applied. Structure refinements on the data sets calculated for these models showed that submicrometer crystals down to 0.5 mu m in diameter are not affected by surface rel axations. Smaller crystals below 0.1 mu m in diameter are significantl y affected by surface relaxations. Great care will have to be taken wh en refining observed intensities of these small crystals.