The critical behavior of the Sugden parameter and the surface tension of simple fluids

Abstract

The capillary rise method has been used to determine the Sugden parameter for the following simple fluids: argon, methane, nitrogen, oxygen, and carbon dioxide. Special emphasis was given to the critical region. The analysis of the data in terms of power laws gives a common critical exponent φ=0.934±0.010 for the five fluids investigated. Combining the critical amplitudes of the Sugden parameter and of the related surface tension with amplitudes of other singular quantities, it was possible to calculate universal constants in the framework of two-scale-factor universality. Universal, system-independent values were obtained for the fluids, but a difference of nearly a factor of 2 is observed with recent second-order ε-expansions and Monte Carlo simulation results.