Experimental and theoretical determination of the L-fluorescence yields of bismuth

Abstract

The knowledge of atomic fundamental parameters such as the mass attenuation coefficients or fluorescence yields with low uncertainties, is of decisive importance in elemental quantification involving x-ray fluorescence analysis techniques. For example, several databases giving the mass attenuation coefficients are accessible and frequently used within a large community of users. These compilations are most often in good agreement for photon energies in the hard x-ray ranges. However, they significantly differ for low photon energies and around the absorption edges of the elements. Some review articles present compilations of measured fluorescence yields values found in the literature. However reliable measurements are not so many illustrating the inherent difficulties. Mass attenuation coefficients of bismuth were determined experimentally in the photon energy range from 100 eV to 30 keV by using monochromatized synchrotron radiation at SOLEIL (France). The fluorescence yields of the three L-subshells of bismuth were also determined using a reflection geometry setup. The application of high-accuracy experimental techniques resulted in low uncertainty mass attenuation coefficients and L-subshell fluorescence yields that are directly compared to existing databases and with updated relativistic configuration mixing Dirac-Fock calculations including QED corrections.

Advances in the measurements of the mass attenuation coefficients

“…New values are obtained with a relative combined standard uncertainty below 2%. We discussed in previous papers the determination of the mass attenuation coefficients for copper and zinc, nickel, germanium, tin, and bismuth . As an example, values for silver are presented as they appear on the website for users on Figure .…”

“…This methodology takes advantage of the accurate and independent measurement of the average mass per area of thin foil samples as well as the large X‐ray spot available at the synchrotron source. Several results were already published in the field for various elements. For every element, the K , L , and M absorption edges were studied more carefully with adapted energy steps in order to describe the absorption fine structures if any.…”

Electron probe microanalysis of transition metals using L-lines: the effect of self-absorption

“…For comparison purposes, self-absorption is also evaluated using a definite mass absorption coefficient, (μ/ρ), which is the conventional approach used in matrix corrections. Figure 1a shows the theoretical Ni Lα emission line (a Lorentzian profile with a natural width of 2.58 eV [5]), and the energy-dependent mass absorption coefficients of metallic Ni measured by Ménesguen et al [6]. Both the emission line and the absorption edge are relatively broad and overlap is considerable; as a result, (μ/ρ)(E) increases rapidly across the X-ray emission line.…”

“…There is a considerable distortion of the line shape when self-absorption is calculated using (μ/ρ)(E), which results in a shifting of the line position towards lower energy and a ~15% increase of its peak height. This suggests that, in this case, even if we know accurately the mass absorption coefficient at the line energy (e.g., from firstprinciple calculations [7] or experimental measurements [6]), errors of up ~15% can still be made if selfabsorption is not accounted for. The observed intensity difference decreases with decreasing incident electron energy and becomes negligible below ~5 keV (Fig.…”

The potential of microcalorimeter X-ray spectrometers for measurement of relative fluorescence-line intensities

“…The dependence of line energies, line widths, and intensity ratios on chemical state have been studied for some lanthanide-series elements [20]. Recent measurements of intensity ratios for several well-resolved L lines have been made for bismuth with a solid-state detector [21], for gadolinium with a high-resolution von Hamos spectrometer [22], and for three actinide elements with a cryogenic microcalorimeter [23].…”