Critical dynamic viscosities in xenon and in the binary mixture nitrobenzene-n-hexane

Ultrasonic shear data along the critical isochore in xenon and in the binary mixture nitrobenzene-$n$-hexane are interpreted in terms of modified theoretical expressions derived within the framework of the decoupled-mode theory. The new expressions mainly arise from separating the real and imaginary parts from the complex dynamic shear viscosity near a critical point. Numerical analysis of the data shows rather satisfactory agreement between theory and experiments for ultrasonic shear data.