The reference intensity ratio, I/I_c, for computer simulated powder patterns

A scale factor γ, to convert from the relative to the absolute/relative intensity scale, is readily calculated during computer simulation of powder patterns. Previously used scale factors are related to γ. The Reference Intensity Ratio, I/I_c (c = corundum), is obtained from μ, ρ, and γ for the sample and for corundum. Comparing calculated and experimental I/I_c values confirms that microabsorption and primary extinction can be serious experimental aberrations possibly limiting the accuracy to several wt.% in quantitative analysis by powder diffraction.