Ultrasonic Three-Phonon Process in Copper Crystal

Abstract

The large angle noncollinear three-phonon interactions have been studied by using longitudinal (L) and transverse (T) pulsed ultrasonics with megahertz frequencies. Two types of process, T[100]+T[\bar110]→L and L[100]+T[010]→L, were observed in the (001) interaction plane of a copper single crystal. The incident ultrasonic beams were approved to be cylindrical in shapes and almost non-diverging. The displacement amplitude of the produced sound was found to be proportional to the product of the amplitudes of two incident sounds, to vary wholly as the cosine of the angle between the polarization direction of T⟨100⟩ incident wave and the interaction plane, being agreed with theoretical predictions. The ratio of the amplitudes of the produced sounds in two types of interaction was disagreed with the theoretical value perhaps due to the difficulty in transmitting the transverse waves into the specimen.