Ultrasonic Propagation in Xenon in the Region of Its Critical Temperature

Abstract

The velocity of ultrasonic waves has been measured in xenon through its critical region. Only the limited frequency range from 250 kc/sec to 1250 kc/sec could be used close to the critical temperature and over this interval a velocity dispersion of as much as 6 percent was observed. The dispersion was accompanied by an abnormally high attenuation of the sound wave confirming in this respect the previously observed behavior of other systems near their critical point. From an analysis of the dispersion measurements it is concluded that structural relaxation processes play a dominant role in the mechanical behavior of the system. The results also indicated the presence of a very wide spectrum of relaxation times.