Multiple scattering of X-rays in the case of isotropic samples

The contribution of multiple scattering in wide-angle X-ray scattering experiments on isotropic samples using Mo Kα and Cu Kα radiation is estimated. The portion of doubly and triply scattered intensity was calculated with a tedious Monte Carlo simulation method and the portion of doubly scattered intensity was calculated with a fast approximate numerical integration procedure. In the case of light elements the correction was found to be important. The approximate method proved to be reliable for thin samples in cases where the cross section for inelastic scattering is small. The effect of the molecular structure of the material on the multiply scattered intensity was demonstrated in the case of liquid sulfur and found to be meaningful at small scattering angles. The correction method was applied to the radial atomic density function (RDF) analysis of water and sulfur. The correction improved the behaviour of the reduced interference function but its effect on the RDF was small in both cases.