Effect of Scattering on the Attenuation of X Rays

The contribution of scattering to the total attenuation coefficient for x rays is considered in crystalline materials. Calculated values of the coherent-scattering coefficient for four commonly used wavelengths and for a number of cubic elements from $Z=6\mathrm{}$ to $Z=42\mathrm{}$ are presented. Measured attenuation of $\mathrm{Mo}K\alpha$ radiation by single-crystal and polycrystalline forms of Mg and Al are reported; the difference in attenuation between the two forms is in agreement with that calculated for Bragg scattering only. The effects of the thermal diffuse scattering on the two forms are comparable. The coherent-scattering contribution is several percent for short wave-lengths and light elements, but it is also appreciable for longer wavelengths and for elements immediately after an absorption edge.