High frequency waves in liquid metals

Abstract

Abstract The inelastic scattering of long wavelength neutrons from coherently scattering metals has been used to examine the collective motions of atoms in the liquid state and to make comparisons with the polycrystalline solids. Well-defined peaks in the velocity spectra of the scattered neutrons have been found in both states for lead, rubidium, tin, bismuth and aluminium. These have been used to present parts of the dispersion curves for vibrational modes of motion in the frequency range 1 to 20 × 1012 rad/sec and wave number range 1 to 3 Å−1, and to estimate lifetimes of the modes of the order 0.4 × 10−12 sec in the solid near the melting point and roughly half these values in the liquid. In polycrystalline aluminium the major contribution to the observed intensity in the solid is due to transverse modes and the observed similarity of the liquid and solid spectra suggests that transverse motions are observed in the liquid also.