Resonant absorption of sound by a metal surface
Zinov'eva K.N.
The angular dependence of the coefficient of transmission of a plane sound wave from He4 into tungsten and gold was investigated at temperatures — 0.1-0.3 K. It is shown that acoustic phonons of frequency 10 and 30 MHz penetrate into the solid only in the region of the pre-critical angle and the angle corresponding to excitation of a Rayleigh wave. The sharp maximum predicted by Andreev and corresponding to resonant absorption of the sound by the surface of the metal is observed in the critical Rayleigh angle.