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| IAEA-CN-115-21 · Optimization of RBS Analysis as an Input for Quantification in X-ray
Abstract: Procedures for the quantitative analysis of thick samples by x-ray emission techniques, such as energy dispersive x-ray fluorescence (EDXRF) or particle induced x-ray emission (PIXE), approach differently the treatment of unknown composition of light elements (low Z analytes with Z<10) in the sample matrix (dark matrix). In PIXE analysis, simultaneous performance of Rutherford backscattering spectrometry (RBS) is today conventionally used to estimate the major matrix element composition needed in the fundamental parameter quantification procedure. Influence of the proton elastic scattering cross section database is discussed here in terms of typical samples analyzed by PIXE. It has been observed that in the case of plant-based samples (including biomonitors) where the major elements in the dark matrix are C, N and O, the existing proton elastic scattering database seems to be sufficiently reliable. Possibilities of RBS to also quantify hydrogen content, by difference, in these samples are also discussed. Optimization of the RBS technique was achieved through measurement and spectra simulation of samples with well-known composition (cellulose, Mylar, Kapton, graphite, and formvar). In addition, the scattering cross-section values used were chosen from Gurbich’s experimental database at scatter angle of 165 degrees. for proton energies at 3 MeV. Validation of the RBS quantification method with the certified reference material Bowen’s Kale gave satisfactory results for the elements H, C, and O. Samples of plant-based reference materials were subsequently analyzed and estimation of the “dark matrix” elemental composition by RBS technique, improved accuracy of the results from the EDXRF analysis.
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