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 meander wire backgammon technology has high levels of flux and spatial linearity across a wide range of energies. One of the attractive features of these technologies is the stability of response and robustness under long X-ray exposure, compactness, and portability. A key problem historically has been the limited range of count-rate for processing to the optimum resolution. We report dramatic advances in this and other areas appropriate for high-accuracy experiments including tests of quantum electrodynamics, fundamental relativistic atomic physics, X-ray calibration, and crystallography. We illustrate this technology applied to the K 1,2 spectra of titanium, chromium, and copper. The quality of the spectra permits deeper insight into atomic and solid state science and permits accurate measurement of energy and relativistic atomic physics processes, below 1-m accuracy or down to 1 ppm in energy. 218 The University of Melbourne (UM) backgammon detector relies on a sophisticated data acquisition system specifically developed for the detector and its use as part of our Johann-type curved crystal X-ray spectrometer. The design allows single photon counting over a wide range of count rates. [30]
A characterization of the Cu K 1,2 spectrum is presented, including the 2p satellite line, K 3,4 , the details of which are robust enough to be transferable to other experiments. This is a step in the renewed attempts to resolve inconsistencies in characteristic X-ray spectra between theory, experiment and alternative experimental geometries. The spectrum was measured using a rotating anode, monolithic Si channel-cut double-crystal monochromator and backgammon detector. Three alternative approaches fitted five Voigt profiles to the data: a residual analysis approach; a peak-by-peak fit; and a simultaneous constrained method. The robustness of the fit is displayed across three spectra obtained with different instrumental broadening. Spectra were not well fitted by transfer of any of three prior characterizations from the literature. Integrated intensities, line widths and centroids are compared with previous empirical fits. The novel experimental setup provides insight into the portability of spectral characterizations of X-ray spectra. From the parameterization, an estimated 3d shake probability of 18% and a 2p shake probability of 0.5% are reported.
We present an absolute energy measurement of the Kβ1,3 (KM2,3) emission spectrum of scandium (Z = 21) accurate to 2.1 parts per million (ppm). The previous experimental uncertainty was estimated as 105 ppm, or 0.47 eV, therefore we improve the accuracy of this measurement by a factor of 50 for use in any x-ray standards. There is a long-standing discrepancy between the most recent experimental and theoretical values. This work reports a Sc Kβ peak energy of 4460.845 eV with estimated standard error uncertainty of 0.0092 eV. The satellite component centroids, line-widths, and relative intensities are determined as a sum of five Voigt functions. The same analysis and experimental method shown here can be applied to advanced experiments in quantum electrodynamics, astrophysics and particle physics on soft x-ray spectra. This value has reconciled some of the previous discrepancy. However, the theoretical value is still discrepant from the new experimental measurement by 1.745 eV with a much tighter constraint on the experimental uncertainty. This strongly strengthens the need for new theoretical calculations and experimental measurements.
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