Determination of slopes of calibration lines in multi element XRF analysis of thin films using polychromatic excitation from Mo, Au, W and Cr anodes and one standard

An algorithm is described for the theoretical calculation of the slopes of calibration lines for the elements of the K-series in multi element X-ray fluorescence analysis of thin films using polychromatic excitation with X-ray tubes producing widely differing primary radiation intensity profiles. The mathematical equations used to calculate slopes as a function of atomic number are based on the fundamental relationship between fluorescent intensity and atomic number, fluorescent yield, concentration and mass absorption coefficients of the analyte for primary radiation. A normalisation procedure based on a single known slope in the series ensured that the calculated slopes were correct for the particular measuring conditions.