Study of non-validity of mixture rule near K-absorption edges by X-ray spectrometric technique

Effective atomic numbers of some tissue substitutes by different methods: A comparative study

“…The mixture rule is not valid near k-absorption edge of the compounds and mixtures. [ 43 44 45 46 ] The mixture rule doesnot consider the molecular, chemical, or crystalline environment of the atom which results in change in the atomic wave-function. With the exception of the fine structure region above absorption edge (>10 keV) errors from these sources are expected to be a few percent, whereas at low energies (10-100 eV), errors of as much as a factor of two can occur.…”

2013 Atomic spectrometry update—A review of advances in X-ray fluorescence spectrometry

“…These data were presented in tabulated form and were tted by analytical functions to deduce new K-shell uorescence yields for a broad range of elements. In a practical study, Sharanabasappa et al 101 experimentally determined the mass absorption coefficients of a group of elements including lead, near the K-shell absorption edges, in the energy range from 17 keV to 88 keV. They observed signicant differences between the experimentally determined coefficients and their theoretical approximations suggesting that Bragg's additivity law (mixture rule) is invalid near the absorption edge.…”