Figure 1

IXS spectra of LB2 and their fits explained in the text. (a) A full spectrum and its central portion $\times 1/20$; (b)–(e) The inelastic part remaining after subtraction of the elastic component determined in a global fit of each spectrum. The lines show the DHO adjustment in this global fit. (f) The inelastic part of a high-$Q$ spectrum treated in the same manner but adjusted to a log-normal reproducing the BP.Reuse & Permissions

Figure 2

(a),(b) The parameters of the DHO fits for the two temperatures 573 and 300 K. The four full dots at 700 K are from 18. The slope of the line in (a) is the BLS velocity measured independently. In (b) the error bars at 573 K are mostly smaller than the symbols, while these at 300 K (not shown) are about twice as large. The line of slope 4 in (b) is drawn through the first five points at 573 K. (c) The integrated inelastic intensities at 573 K, corrected for the oxygen-ion form factor, with a line $\propto Q^2$. (d) The method used to determine ${\Omega }_{\mathrm{IR}}$ applied to LB2 (these data) and $d\mathrm{\text{−}}{\mathrm{SiO}}_2$ (data from 11). The straight lines are guides to the eye. The crossover positions are at the intercept with the ordinate $1/\pi$.Reuse & Permissions

Figure 3

${\Omega }_{\mathrm{IR}}$ vs ${\Omega }_{\mathrm{BP}}$ for various glasses. The line ${\Omega }_{\mathrm{IR}}={\Omega }_{\mathrm{BP}}$ is a guide to the eye. The points and the references for $\Gamma (\Omega )$ and ${\Omega }_{\mathrm{BP}}$ are (1) ${\mathrm{Li}}_2\mathrm{O}\mathrm{\text{−}}2{\mathrm{B}}_2{\mathrm{O}}_3$, here and 18, 23; (2) ${\mathrm{Li}}_2\mathrm{O}\mathrm{\text{−}}4{\mathrm{B}}_2{\mathrm{O}}_3$ [18, 23]; (3) $d\mathrm{\text{−}}{\mathrm{SiO}}_2$ [10, 11]; (4) vitreous silica $v\mathrm{\text{−}}{\mathrm{SiO}}_2$ [14, 31]; (5) polybutadiene [38, 39]; (6) polycarbonate [40]; (7) Se [41, 42]; (8) glycerol [43, 44]; (9) ethanol [7, 45]; (10) OTP [46, 47].Reuse & Permissions

Figure 4

$\Gamma (\Omega )$ for LB2, showing the IXS results with the line of slope 4 from Fig. 2b, and our own BLS measurements. The lines are guides to the eye discussed in the text. The error bars are smaller than the symbols, also in the inset.Reuse & Permissions