Figure 5.19. Critical contribution to sound attenuation (αλ_crit) at T = 27.81 °C.

Figure 5.20. Sound attenuation.

The data are now fitted again, with A_BF treated as a free parameter and ω_BF varied until the experimental data fall on the theoretical function F_BF. The sound velocity c_s is specified from the resonator measurements. The fit uses the experimentally determined critical temperature from light scattering, T = 300.84 K = 27.69 °C, because the critical temperature obtained from the ultrasonic measurements is uncertain.