The influence of the divergence of X-rays on the determination of volume of diffracting particles

Abstract

The relation was investigated of the number of diffraction spots from unit volume of a polycrystal to the mean instrumental divergenceα _m of X-ray beam. Experimental evidence proves this dependence to be decreasing, in contradiction to the generally accepted theoretical basis of the method. These experimental results mean an increasing effective volume of diffracting particles with increasing instrumental divergence. Thus the application of the quantityα _m itself distorts the true dependence of number of spots on instrumental divergence. We shall prove this statement and shall apply the previous experimental results to infer more detailed ideas on the mentioned dependence, while using the instrumental divergenceα instead of the mean valueα _m .

This detailed analysis of experimental results contributes to better understanding of the method and suggests the precautions to be taken in the interpretation of results when determining the volume of diffracting particles from spotty diffraction lines.