Relative X-ray line intensities and their application to a single standard procedure for quantitative X-ray microanalysis of bulk samples and thin films.

摘要

X-ray spectra collected by an energy dispersive spectrometer on an electron microprobe analyzer were fitted to determine relative line intensities between elements for a wide range of atomic numbers. The relative line intensities within spectral series for K, L and M lines were also obtained. In the case of Kalpha lines an empirical formula is proposed for the prediction of generated line intensities of pure element standards relative to that of Cu Kalpha at 20keV used as a reference standard, although other line references can be used for lower beam energies. The generated ratios can be predicted with accuracy generally better than 2% relative to the actual measured values. The relationship covers elements with atomic numbers in the range of 12 (Mg) to 32 (Ge) and incident beam energies between 5 and 20keV. Unfortunately, L and M line data could not be fit with the same level of accuracy to a single expression due to the inherent variability in the data as a function of atomic number. These data are therefore presented in tabular form. The availability of relative line intensity measurements as a function of atomic number makes it possible to perform accurate quantitative X-ray microanalysis with the measurement of a single standard rather than a separate measurement of each element standard. As a result not only are measurement times shorter, but it is also possible to estimate values for elements for which pure standards may not be available. Furthermore, the method has been extended to quantitative analysis based only on the measurement of the sample spectrum. In addition, the knowledge of K-ratios as a function of film thickness makes it possible to develop calibration curves that can be used to nondestructively determine film thickness. The case of a pure element is studied on a given substrate, and extending the concept to multi-element films can provide a way to obtain both thin film composition and thickness. In the last section, currently available, state of the art, X-ray simulation packages are evaluated for their predictions on X-ray yields from bulk standards and thin films.