For purpose of comparison, here is a histogram for B Ka k_calc/k_meas constructed using the PROZA96 model of Bastin et al. (1998, X-ray Spectrometry 27:3-10) in conjunction with experimental data and MACs presented in

Bastin and Heijligers (1997). The mean is 1.0026, and the RMS deviation is 0.0329; these values are similar to those presented by Bastin et al. (1998). The RMS deviation is slightly better than that obtained from PAP using the same empirical MACs or the Bastin MACs contained in the CalcZAF file empmac.dat and is considerably better than that obtained from

PROZA.

I should note that I had to integrate numerically (Simpson’s rule) to obtain F(chi) due to precision issues in evaluation of exponential and error function terms in the analytical expression for emitted intensity (with generated intensity determined using PAP). Imprecision becomes an important factor when the MAC is large relative to the values of the model alpha and beta parameters and can result in erroneous calculation of f(chi) = 0. I’m not sure how Bastin et al. (1998) got around this problem. Their “double-Gaussian” phi(rho*z) model is adapted from Merlet (1994, Mikrochimica Acta 114/115:363-376), and this is how it looks (from Bastin et al., 1998):

When I apply the FFAST MACs instead of those presented by Bastin and Heijligers (1997), I get horrible results. The FFAST MACs are systematically low compared to the empirical MACs. The resulting mean k_calc/k_meas is 1.1234, and the RMS deviation is 0.2821.

I’ve determined FFAST MACs for B Ka in a given pure element by polynomial interpolation of the tabulated calculated values available at the

NIST website (NIST Standard Reference Database 66, updated August 2005). The values that I get differ slightly from those used in CalcZAF, but generally the differences are small compared to the differences with the MACs of Bastin and Heijligers.

This leads to a question: Regarding the chantler2005-xx.dat files, exactly how were the FFAST MACs for a given X-ray line in a given matrix determined? In the plot below for a pure Zr matrix, the black dots are the tabulated values from NIST, the red dots are the values I get by means of polynomial interpolation, and the blue dot is the MAC for B Ka in Zr according to CalcZAF.

Edit 2016-02-24: When I initially performed the numerical integration to obtain F(chi) for pure boron, I set the upper limit of integration a little too low. I've corrected this and have replaced the histograms with new ones. Using the MACs from Bastin & Heijligers (1997), the mean and RMS deviation are now improved slightly.