Low-frequency optical dielectric response and rigidity transitions in network glasses

Abstract

Self-organization occurring in ${\mathrm{As}}_{x}{\mathrm{S}}_{1\ensuremath{-}x}$ and ${\mathrm{As}}_{x}{\mathrm{Se}}_{1\ensuremath{-}x}$ glass alloy films reflects in their low-frequency optical dielectric response, and valuable information about the building blocks conforming their structure, can be derived from the analysis of the refractive-index dispersion data. The experimental results are discussed in the framework of the single-oscillator approach proposed by Wemple and DiDomenico, which provides a meaningful parametrization of the phenomena ruling the coupling between the photon-probe and the electron plasma in the near-infrared spectral region. Rigidity transitions occurring in both binary glassy systems are discussed in terms of the differences observed in the oscillator parameters, and these electronic evidences are linked to those arguments found in the literature, based on calorimetric and Raman measurements, that point to a segregated-phase view of glass materials.