Combined multiple-excitation FP method for micro-XRF analysis of difficult samples

Accurate minor and trace element analysis via micro-XRF can be more difficult to accomplish in single crystal and polycrystalline materials due to diffraction phenomena which obscure elemental peaks and distort the spectral background. A primary-beam filter is commonly used to eliminate diffractive artifacts as well as tube characteristic lines, but this dramatically reduces the sensitivity to lighter elements. One way around this is to collect a spectrum with unfiltered excitation to obtain the low-energy region, i.e., Na, Mg, Al, and Si, and then collect other portions of the spectrum under more optimized conditions. The fundamental parameter method is capable of using multiple spectra to quantify the complete element suite of the sample. By unifying the quantification for several spectra taken under different excitation conditions, the overall results can be improved. We have applied this method to selected cases for geological and metallurgical samples. The combined method gives better results for all elements than the single spectrum quantification as judged by agreement with the values from the supplier.