Collective modes in molten CsCl, CuCl and AgI observed by inelastic x-ray scattering

Inelastic x-ray scattering measurements have been carried out for molten CuCl and AgI and the results were compared with those in molten CsCl by Inui et al. (2007) [42]. The inelastic components arising from collective excitation were observed on both sides of the quasielastic component at the center in the dynamic structure factor. As a result of examining several model functions to fit the observed dynamic structure factor with convolution of the spectrometer resolution function, we adopted the conventional damped harmonic oscillator with a Lorentzian for the quasielastic component. From the apparent sound speed and the linewidth of the collective excitation, the ionic dynamics of molten AgI was found to be different from that in molten CsCl and CuCl, suggesting that AgI has the strongest covalent bonding nature among these molten salts. Meanwhile the relaxation times estimated from the width of the quasielastic components indicated that ionic dynamics in noble metal halides differs from that in molten CsCl.