High accuracy characterisation for the absolute energy of scandium Kα

Abstract

This work reports the absolute characterisation of the Sc Kα profile. All component peaks are characterised for the first time. The satellite component centroids, line-widths, and relative intensities are determined. Energies are calibrated on an absolute basis. Sc and peak energies of 4090.699(10) eV and 4085.926(18) eV are reported, respectively, with estimated standard error uncertainties of 2.4 and 4.4 ppm. In this work, an electron gun operating at 20 kV, incident on high purity metals, produces the x-ray fluorescence, which Bragg diffracts via a Germanium (220) crystal to permit high-accuracy measurement of energy. The Kα emission spectrum of scandium (Z = 21) has not been measured in absolute energy in over 50 years. At the time the data was reported in ‘x units’ and the angstrom was not a well defined unit. That reported uncertainty was estimated to be approximately 50 ppm (parts per million) or 0.2 eV. The new profile characterisation combined with the absolute energy calibration provides an important definition for future studies in chemical speciation and condensed matter studies. Furthermore, the methodology described obtains a level of accuracy from relatively low energy x-rays to provide an important insight for future studies in fundamental parameters, pionic spectra and high-accuracy tests of QED.

The characteristic radiation of copper Kα1,2,3,4

“…It is instructive to consider this in relation to the range across the periodic table, Fig. We would expect the component ratio to be less for Sc than for Cu and this is true from the recent determination by Dean et al (2019). We would expect the component ratio to be less for Sc than for Cu and this is true from the recent determination by Dean et al (2019).…”

Vignetted photon fields, recharacterisation of V Kα, and reducing X‐ray uncertainties by a factor of two

“…These clinometers are calibrated to great angular precision to obtain a precise dispersion function and therefore energy, using well‐defined literature values for other transitions in a similar region to the target transition. We show the transitions used by a recent publication [ 16 ] with the aim of characterising Sc K α in Table 3.…”

“…C [ 18 ] and, for example, ref. [16] as well as papers sourced in those references. Hence, it is common in recent literature for 3d transition metals to be described with six Voigts for K α and five for K β .…”

“…[ 14 ] Another method uses a Johann‐type (curved) crystal spectrometer, with a strained lattice spacing, so must be calibrated to provide a reliable relationship between angle and energy. [ 15,16 ]…”

“…Furthermore, it has enabled some experiments to report uncertainties a factor of two lower which have enabled measurements to be taken with precisions not previously possible. [ 16 ]…”