ULTRASONIC SPECTROSCOPY
Department of Physics
Resonant Ultrasound
Developments over the past decade have led to a renaissance in the ultrasonic spectroscopy of solids. Most of the activity is centered on a new technique known as resonant ultrasound spectroscopy (RUS). Whereas conventional ultrasonic techniques rely on the propagation of plane waves with resultant sample dimensions of the order of centimeters, RUS is based on the measurement of the vibrational eigenmodes of samples of well-defined shapes, usually parallelepipeds or spheres. The vibrational eigenmodes for rectangular parallelepipeds illustrated on these pages were computed by Dr. Frank WIllis, a former student in the group. RUS has several features which make it especially attractive for condensed matter physics studies.
- Rather small samples may be used. Reliable measurements are possible on samples of mm dimensions, or smaller.
- There is no bond between the transducer and the specimen. The result is that temperature dependent data become much easier to acquire because the problem of differential thermal contraction of the bond, specimen, and transducer is avoided.
- All the elastic constants, even for low-symmetry materials, can be determined from one spectrum on one specimen.
- Typical millimeter-size samples result in resonant frequencies of a few hundred kHz to a few MHz. As a result, RUS is sensitive to dynamic processes in this frequency range, a range difficult to access by many other techniques.
Additonial information may be found in the following articles.
A. Migliori, J. L. Sarrao, W. M. Visscher, T.M. Bell, M. Lei, Z. Fisk, and R. G. Leisure, "Resonant Ultrasound Spectroscopic Techniques for Measurement of the Elastic Moduli of Solids," Physica B 183, 1 (1993).
J. Maynard "Resonant Ultrasound Spectroscopy," Phys Today 49, 26-31 (Jan 1996).
A. Migliori and J. L. Sarrao, Resonant Ultrasound Spectroscopy (Wiley, New York, 1997).
