Corrections to scaling in the small-angle x-ray scattering from argon near the liquid-vapor critical point

Abstract

The equations giving the first corrections to scaling in the small-angle x-ray and neutron scattering near the liquid-vapor critical point [P. W. Schmidt and M. Chandrasekhar, Phys. Rev. B 24, 2773 (1981)] have been fitted to the small-angle x-ray scattering curves from argon obtained by G\"urmen et al. [Phys. Rev. A 22, 170 (1980)]. This reanalysis of the scattering data shows that when the values of the critical exponents obtained from theoretical calculations are used in the equations for the critical scattering, corrections to scaling clearly are present. The correction amplitudes for the isothermal compressibility and long-range correlation length have been evaluated. Another correction amplitude has been obtained from the outer part of the critical scattering curve. From the first two of these amplitudes and the correction amplitude determined from an analysis of the form of the liquid-vapor coexistence curve, two ratios of correction amplitudes can be calculated. These ratios are not in good agreement with those obtained from theoretical calculations. Some possible causes of this disagreement are suggested.