Evaluation of a practical background calculation method in X‐ray energy analysis

Abstract

Before investigating the applicability and the eventual causes of failure of the background correction using incoherent and coherent scatter peaks, it is necessary to examine in detail the different contributions to the XRF spectrum background.The background beneath the fluorescence lines of energy dispersive X-ray spectra obtained with a molybdenum secondary target tubeexcited system can be obtained from the intensities of the coherently and incoherently scattered radiation. The background intensity at a particular energy is equal to the product of a proportionality factor multiplied by the incoherently scattered radiation intensity, plus another proportionality factor multiplied by the coherently scattered radiation intensity. The proportionality factors are determined from measurements of a number of molybdenum-loaded cellulose filters.The proposed procedure provides accurate results for the analysis of complex X-ray spectra of thin samples of varying composition. TheoryWhen monoenergetic X-rays strike the detector, the spectrum consists of discontinuous features such as the full energy peak and the escape peak and a continuous spectral component. The latter consists of first, the

Scanning macro x‐ray fluorescence spectroscopy maps for matching 17th century paintings color areas to different earth pigments uses and for investigating attribution issues

“…Last but not the least, if the radiation of Mn and the radiation of Fe originate from the same layer, their intensity ratio reflects (together with a correction factor depending on the excitation spectrum and layer thickness) their respective concentration ratio. The composite x‐ray spectrum found in fluorescence analysis does not only depend on the mass and chemical composition of the sample but also on the excitation conditions and sample thickness 41,42 . In this regard, the smaller the thickness of the sample, the more negligible are the absorption effects.…”

“…The composite x-ray spectrum found in fluorescence analysis does not only depend on the mass and chemical composition of the sample but also on the excitation conditions and sample thickness. 41,42 In this regard, the smaller the thickness of the sample, the more negligible are the absorption effects. Furthermore, absorption happening in the detector windows also affects the relative intensities of the lines.…”

High Definition X‐Ray Fluorescence: Principles and Techniques

“…These have traditionally involved use of standards of known composition [39,40] to calibrate the measurement system which must always take into account the detection method, geometry, and sample form. For conventional X-ray fluorescence, the analysis is complicated by the presence of a large Bremsstrahlung continuum which also reduces measurement sensitivity and requires background evaluation methods [41,42]. As noted in Section 1, introduction of monochromatic X-ray excitation dramatically improves the signal-to-background (S/B) ratio for trace element determinations by eliminating the background due to scattering in the sample of Bremsstrahlung radiation from the X-ray source.…”

Absorption correction via scattered radiation in energy-dispersive x-ray fluorescence analysis for samples of variable composition and thickness

“…The absorption of the primary and fluorescent radiation is far more important than the grain size, enhancement and scatter effect, when large particles are absent in a matrix of predominantly light elements. In recent years, a number of approaches (1)(2)(3)(4)(5)(6) have been employed to account for matrix absorption effects in trace analysis, by either wavelength-dispersive or energy-dispersive methods. Since the pioneering work of Andermann and Kemp (7), the information about the sample matrix contained in the scattered X-rays has been exploited in several ways to determine the spectral background (8,9), the matrix absorption effects (10)(11)(12)(13)(14)(15)(16)(17)(18)(19), and the sample mass (20,21). An excellent review on correction methods based on scattered radiation was recently published by Nielson (10), who notes that absolute scatter intensity methods, where a correlation is made between the scattered intensity and a certain parameter, yield more information to correct for the matrix effect than the relative intensity methods, which rely only on the fluorescent/scatter intensity ratio.…”

“…In practice a straight line, eq 8, derived by means of a least-squares fit, is used to calculate the mass absorption coefficient of the sample to be analyzed. µ(2.956 keV) = -90.0 + 640fi (8) Total Absorption Correction Procedure. Although mass absorption coefficients at other energies could be obtained on the same basis as µ(2.956 keV) in eq 8, another more practical procedure has been developed.…”