Ultrasound absorption due to electrons and phonons in alkali liquid metals

Abstract

The excess longitudinal ultrasonic absorption over and above the classical value in four alkali liquid metals near their melting points has been accounted for by the mechanisms of interaction of sound waves with the conduction electrons and the thermal phonons (Akhieser mechanism), both exhibiting a quadratic dependence on sound frequency. An expression, similar to the Bridgman relation for liquids, for the phonon conductivity in the liquid metals has been developed. This approach briefly reported here yields good results.