Strain-field scattering of fast-transverse acoustic phonons by dislocations in LiF

The mean-free-paths of transverse acoustic phonons generated in surface hot spots and propagating ballistically along [100] in LiF are calculated exactly for the case of scattering by the static strain fields of edge and screw dislocations of Burger's vector $\text{1}\text{2}\text{a [}\text{1}\text{10}\text{]}$. Due to wavevector conservation the screw dislocations are shown not to scatter such phonons at all while the edge dislocations lead to mean-free-paths greater than 12 cm for dislocation densities ?2×10⁸ cm^-2 and frequencies ?5×10¹¹ Hz. This is consistent with the observation by Northrop et al. (1982) of the ballistic propagation of such heat-pulse phonons across deformed crystals of 1 cm dimensions.