COMPLEX PROPAGATION OF SURFACE-WAVES ON SOFT GELS

A spectroscopic study of surface waves was made on gels of gelatin and agarose over the frequency range 10(1)-10(6) Hz. Two different optica l techniques, the ripplon light scattering and the induced-surface-wav e measurement were used for the appropriate frequency range. The dispe rsion curve determined for the gelatin gel showed that surface-tension waves appear in a frequency range higher than 20 kHz in spite of its solidity, while surface elastic waves propagate at frequencies lower t han 300 Hz. As for the waves in the intermediate region, a theoretical prediction suggested coexistence of both waves though it was not conf irmed experimentally. A similar result was obtained also in an agarose gel.