Dynamics of a mercury prewetting film near the prewetting critical point

Abstract We studied the dynamics of a mercury prewetting film near the prewetting critical point by using dynamic light scattering techniques. Relatively strong relaxation is observed in the prewetting region, and its time scale is about 101–103 ms. The oscillatory behavior of the observed autocorrelation function strongly suggests that the light is scattered by the surface wave formed on the surface of the prewetting film. When the temperature is lower than the prewetting critical temperature Tcpw, both the frequency and the relaxation rate monotonously increase with decreasing pressure, accompanied by a decrease of the thickness of the prewetting film. When the temperature is slightly higher than Tcpw, on the other hand, the frequency and the relaxation rate show minimums near the prewetting critical point. This is clear evidence for the critical slowing down.