Elemental X-Ray Cross Sections at Selected Wavelengths

Abstract

Revised tables of x-ray mass attenuation and absorption cross sections have been prepared for the elements with atomic numbers one to 94 at selected wavelengths of interest to spectroscopists, microprobe users, diffraction workers, etc. The tables are derived from an x-ray cross section compilation to be published during the summer of 1971. The new compilation is a revision of a previous work and provides photoelectric, coherent scattering, incoherent scattering, absorption component of incoherent scattering and total attenuation cross sections for 94 elements for the photon energy range 0.1 keV to 1 MeV (0.0124 Å to 124 Å). The cross sections for energies greater than 1 keV (12.4 Å) were determined from experimental attenuation data and theoretical scattering cross sections calculated using form factors and incoherent scattering functions based on a relativistic self consistent field method. For hydrogen, the photoelectric absorption cross sections were calculated exactly. Least squares procedures were used to interpolate and extrapolate for elements and photon energies where no experimental data were found. Cross sections for the energy range 0.1 keV to 1 keV (12.4 Å to 124 Å) were calculated using nonrelativistic, single electron, self-consistent field theory with Herman-Skillman bound state wavefunctions, A brief description is given of the assumptions and methods used in preparing the revised compilation, and estimated uncertainties in the cross section are reported. Examples illustrating agreement between tabulated values and experimental data are given and a comparison is made with values taken from earlier x-ray cross section compilations.

Pressure-Dependent Electrochemical Behavior of Di-Lithium Rhodizonate Cathodes

“…The structure of the redox-inactive phase likewise consisted of hexagonally close-packed rhodizonate layers; however, adjacent layers were offset in an ABAB stacking pattern in the stacking order exhibited by Na 2 C 6 O 6 (Figure 6b). 49 As the Li coordination could not be determined directly from experimental data, 50 structures were considered, with Li + occupying sites either within the rhodizonate layer or within the VDW gap (Figure S13). The correct Li + coordination assigned to the configuration, which most closely resembled the experimentally obtained diffraction patterns.…”

X-ray absorption and emission

“…Massaging of existing data with various admixtures of theoretical values continues, however, and it does seem that the recent tabulations (40,41) give better values over a large range of wavelengths and elements than did earlier compilations. The best estimates of accuracy are 1 to 2% for some elements for the 0.7 to 2 Á range, 2-5% for most elements for the ¡0.2 to 5 Á range, >10% for all elements jfor wavelengths greater than 5 Á and near the absorption edges.…”