λ/2 contamination in X-ray diffraction data – the impact of heavy atoms

The impact of very different values of f′ and f′′ and of absorption coefficients for the wavelengths λ and λ/2 for heavy elements, and the effect of the difference in wavelength dispersion on the profile of the corresponding Bragg reflections, are discussed with respect to the correction of diffraction data for λ/2 contamination. The impact on the results of four charge-density studies is discussed.