Transient grating studies of ultrasonic attenuation in reverse micellar solutions

We report measurements of ultrasonic attenuation in reverse micelle solutions of water in isooctane, heptane, or decane at gigahertz frequencies using the picosecond transient grating method. The diameters of the micelles ranged from 2.5 to 12.0 nm. The water pools comprising the interior of the micelles enhance the acoustic attenuation constant depending on the concentration and size of the micelles. The additional attenuation resulting from the micelles is consistent with predictions of existing theories of thermal, viscous and scattering contributions to acoustic wave attenuation, which, previously, found verification only at lower acoustic frequencies. (C) 1997 Published by Elsevier Science B.V.