Ultra high frequency acoustic waves

Abstract

Two different experimental techniques are available for making ultra-high-frequency acoustic measurements. These are (i) the study of light-scattering (for solids and liquids), and (ii) the use of microwaves (so far mainly restricted to solids). The first method does not require an acoustic source or generator, but makes use of the natural Debye waves; the results show that for someliquids it is possible to observe the effects of non-elastic molecular collisions. The second method has so far been applied chiefly to quartz, but is already yielding some information on the nature of the anharmonic interactions between atoms in a crystal.