X-ray mass attenuation coefficients and imaginary components of the atomic form factor of zinc over the energy range of 7.2–15.2 keV

Abstract

X-ray mass attenuation coefficients and imaginary components of the atomic form factor of zinc over the energy range of 7.2-15.2 keVThe x-ray mass attenuation coefficients of zinc are measured in a high-accuracy experiment between 7.2 and 15.2 keV with an absolute accuracy of 0.044% and 0.197%. This is the most accurate determination of any attenuation coefficient on a bending-magnet beamline and reduces the absolute uncertainty by a factor of 3 compared to earlier work by advances in integrated column density determination and the full-foil mapping technique described herein. We define a relative accuracy of 0.006%, which is not the same as either the precision or the absolute accuracy. Relative accuracy is the appropriate parameter for standard implementation of analysis of near-edge spectra. Values of the imaginary components f of the x-ray form factor of zinc are derived. Observed differences between the measured mass attenuation coefficients and various theoretical calculations reach a maximum of about 5% at the absorption edge and up to 2% further than 1 keV away from the edge. The measurements invite improvements in the theoretical calculations of mass attenuation coefficients of zinc.

Collision-induced amplification of radiation in inversionless two-level systems

“…Unlike the Si data, this set shows closer agreement to the XCOM predictions, though the data dip towards the FFAST predictions just above the Al Kα x-ray energy. This effect is similar to a trend observed below the K edge for four previously mentioned experiments: Ag [23], Mo [24], Cu [25] and Zn [26]. In each case, the data in this energy region agree with XCOM but drop to midway between the two theories, into slightly closer agreement with FFAST, in the vicinity of the Kα energy.…”

“…A recent and extensive set of synchrotron radiation measurements has appeared [20][21][22][23][24][25][26][27][28] in which the authors demonstrated painstaking effort to eliminate systematic errors identified in earlier measurements [15][16][17]. They examined attenuation coefficients for elements Si, Cu, Zn, Ag, Mo, Sn and Au with generally an overall five-fold improvement in measurement accuracy (typically to within 0.1-0.2%) with respect to earlier work.…”

“…They examined attenuation coefficients for elements Si, Cu, Zn, Ag, Mo, Sn and Au with generally an overall five-fold improvement in measurement accuracy (typically to within 0.1-0.2%) with respect to earlier work. This has allowed, for the first time, a critical analysis of the available theories, generally extending from the K edge of each element and upward in energy; coefficients immediately below the K edge for Ag [23], Mo [24], Cu [25] and Zn [26] were also included. Another consideration made was to incorporate measurement energy spacings at close enough increments near the K edges to show fine structure detail.…”

Absolute determination of the X‐ray absorption coefficient of barium in the L region using a liquid absorption cell

“…The simple picture is modified by possible effects of beam harmonic contamination and of dark current drift of the detectors with the contribution ε ( E ) to the transmitted beam: A i ( E ) = −ln[ ε ( E ) + exp(− μ ( E ) d i )]. Now, the ratios R are not constant: any variation in the ratio, especially any residual of the edge or XAFS features, indicates a contamination.…”

“…The compilations claim a 1% accuracy in the »smooth« energy regions far from absorption edges and 4%–20% in the vicinity of the absorption edges even in monatomic gases free of XAFS modifications of the absorption. Direct measurements have since only been performed on a few selected elements for the purpose of recalibration of compiled data or in conjunction with inner‐shell atomic spectroscopy . It has been realized that with the advance of X‐ray sources and detectors, the accuracy of the absorption coefficient depends mostly on the definition of the sample rather than on the spectroscopic measurement itself.…”