Medium-range order in glasses: Comparison of Raman and diffraction measurements

The correlation lengths of vitreous structures estimated from the low-frequency (boson) peak in Raman spectra and from the width of the first sharp diffraction peak are compared. This first comparison shows that the two estimates, which are based on dynamic and static properties, respectively, are in good quantitative agreement. The present result supports the concepts that (a) a decisive scale for structural order in glasses is \ensuremath{\sim}10 \AA{}, and (b) the low-frequency excitations are defined by the characteristic length in vitreous structures.