Landau and Rumer (1937) have considered the attenuation resulting from a particular three phonon process involving a shear acoustic phonon, and have shown that the attenua- tion coefficient should have the form I' = A w T^4 ; where r is the attenuation coefficient, w relates to the acoustic wave, T is the temperature and A is a function of the elastic anharmonicity of the material under investigation.
\cite{price_acoustic_1971} \cite{landau_absorption_1937}
#a-Si
##1 ns
##10 ns
