LIGHT-SCATTERING AND DIELECTRIC SUSCEPTIBILITY SPECTRA OF GLASSFORMING LIQUIDS

We propose a simple explanation for the marked difference in the spect ral shapes of the dielectric and the depolarized light scattering susc eptibilities of the fragile molecular glassforming liquids: it is the direct consequence of the probing of the same molecular orientational dynamics through techniques having different tensorial properties. We deduce a relationship between the corresponding nonergodicity paramete rs which is well verified in molecular dynamics simulations available so far. We also show that the corresponding orientational susceptibili ties of the NO(3)(-)ions in the glassformer CKN, obtained in a recent simulation, exhibit the same spectral difference as in the molecular l iquids.