Numerical description of photoelectric absorption coefficients for fundamental parameter programs

Abstract

After a systematic analysis of different databases and a comparison with empirical data, we decided to describe photoelectric absorption coefficients, coherent and incoherent scattering coefficients and mass attenuation coefficients in the energy range from 1 to 300 keV for elements from Z = 1 to 94 by a modified version of Scofield's tables in combination with scattering coefficients from Elam et al. Modifications include check and correction of edge positions, description of M 4 -and M 5 -ranges of elements from promethium upwards by sawtooth responses and reduction of data by introduction of least-squares fits of fifth order to Scofield's and Elam et al.'s numerical data. Our database was developed especially for application in fundamental parameter programs for quantitative x-ray analysis (XRFA, EPMA, XPS and TEY).We start by looking at the classical McMaster tables. 2 Elements from Z D 1 to 83 and elements Z D 86, 90, 92 and 94 are contained and photon energies cover the range from 1 keV to 1 MeV. Essential data are conversion from b/a to cm 2 g 1 , K-and L-edge positions and corresponding jumps, third-order least-squares fit coefficients of photoelectric absorption in K-, second-order fit coefficients in L-and

Theoretical and experimental determination of K - and L -shell x-ray relaxation parameters in Ni

“…The resulting ratio of 1 : 1.92 is in good agreement with the expected value of 1 : 2 for the population ratio between the 2p 1/2 and the 2p 3/2 orbitals. Above the L 1 edge the partial PECS of Ebel et al [51] were used to extrapolate the contributions of L 3 and L 2 , see the dashed lines in Fig. 2.…”

Quantification in X-Ray Fluorescence Spectrometry

“…(9) enables to calculate the intensity of fluorescent radiation of analyte in the specimen of known composition. It is possible if all physical constants are known: photoelectric absorption coefficients, mass-attenuation coefficients, Cöster-Kronig transition probabilities, fluorescence yields, weight of analytical line within the series, absorption jump ratios, whose values can be found in updated databases (Elam et al, 2001;Ebel et al, 2003). X-ray tube spectrum, required in calculation, can be obtained from published experimental data.…”

The Oxidation State of Europium in Hydrothermal Scheelite: In Situ Measurement by Xanes Spectroscopy

“…X-ray yields and relative intensities refl ect sub-shell ionization cross-sections, Coster-Kronig transition rates for the L shell, and fl uorescence yields. Sub-shell absorption cross-sections use the recent compilations of Ebel et al (2003), and the Coster-Kronig rates, fl uorescence yields and branching ratios rely on the fundamental parameter database of Elam et al (2002).…”