INELASTIC NEUTRON AND RAMAN-SCATTERING OF POLY(METHYL METHACRYLATE) -NANOSTRUCTURE OF POLYMER GLASSES

Low-energy excitations were investigated in amorphous poly(methyl meth acrylate) by means of both neutron and Raman scatterings, in a wide te mperature interval. The frequency dependence of the light-vibration co upling coefficient was deduced, especially at low temperature where th e quasi-elastic contribution is not significant; it was not found to b e linear. The vibrational density-of-states anomaly is interpreted in the frame of a non-continuous glassy nanostructure, which is character ized by a log-normal size distribution of domains.