Ultrasound absorption studies in the critical region of lithium-ammonia solutions

Measurement of the absorption of ultrasound in the critical region of lithium-ammonia solutions as a function of concentration, frequency, and temperature are presented. The absorption reaches a maximum at 4.2 mole percent lithium and is a function of the frequency. The frequency dependence can be explained either by a single relaxation at around 20 MHz or by using Fixman's theory with a correlation length of 51.3 Å.