Volume 104, Issue 6, December 1998
Index of content:
- ULTRASONICS, QUANTUM ACOUSTICS, AND PHYSICAL EFFECTS OF SOUND 
104(1998); http://dx.doi.org/10.1121/1.423918View Description Hide Description
Elastic constants of the lithium tantalate crystal were determined in the hypersonic range by the use of the Brillouin laser light scattering method. Obtained values show variation with respect to ultrasonic measurements. Results are interesting because the same effects are qualitatively different in isomorphic lithium niobate crystal.
104(1998); http://dx.doi.org/10.1121/1.423919View Description Hide Description
To understand behavior of surface waves on sols and gels, the dispersion relation of surface modes on isotropic materials with both surface tension and elasticity is studied. The dispersion relation consists of two separate branches: one corresponds to the truly localized Rayleigh-type modes which can exist only at low frequencies, while the other, which is connected continuously to the capillary modes, gives pseudo-surface waves that are damped, radiating elastic transverse waves into the bulk of the medium just like the ones known in surface waves on elastically anisotropic materials. The result is compared with recent experiments on sols and gels.