Inelastic light, neutron, and X-ray scatterings related to the heterogeneous elasticity of glasses

摘要

The effects of plasticization of poly(methyl methacrylate) glass on the bosonpeaks observed by Raman and neutron scattering are compared. In plasticizedglass the cohesion heterogeneities are responsible for the neutron boson peakand partially for the Raman one, which is enhanced by the compositionheterogeneities. Because the composition heterogeneities have a size similar tothat of the cohesion ones and form quasiperiodic clusters, as observed by smallangle X-ray scattering, it is inferred that the cohesion heterogeneities in anormal glass form nearly periodic arrangements too. Such structure at thenanometric scale explains the linear dispersion of the vibrational frequencyversus the transfer momentum observed by inelastic X-ray scattering.