ULTRASONIC AND LIGHT-SCATTERING STUDIES OF BENZENE

A detailed examination of ordinary Brillouin light scattering in liquid benzene at 25°C reveals that no single total relaxation of all the vibrational modes can make the ultrasonic absorption data consistent with the light-scattering data. Consistency can be achieved, however, by assigning a viscosity η1=0.845P and a relaxation time τ 1″=2.98×10-10 sec(f1″=533 MHz) to all the vibrational modes except the lowest; and η2=0.07P with τ2″=3.6×10-11 sec(f 2″=4400 MHz) to the degenerate lowest mode. The volume viscosity ηv, is equated to 4/3ηg and ηv+4/3ηg), is made a relaxing viscosity η3 with τ3″=10-12 sec.