DENSITY-FLUCTUATIONS IN AMORPHOUS SYSTEMS - SAXS AND PALS RESULTS

The electronic density fluctuations in polymethyl methacrylate (PMMA) were studied by synchrotron radiation small angle X-ray scattering (SA XS), and compared with the hole volumes as revealed by positron annihi lation lifetime spectroscopy (PALS). The results of both methods are s hown to be compatible with a structure of the liquid and the glass wit h local heterogeneities of radius of the order of 0.3 nm. These micros tructural investigations thus support the existence of density fluctua tions in amorphous systems on a nanometer scale. (C) 1998 Elsevier Sci ence B.V. All rights reserved.