The structure of Kα hypersatellite spectra of Cu, Ni and Fe as a test of intermediate coupling

Briand, Jean‐Pierre; Touati, A.; Frilley, M.; Chevallier, Pierre; Johnson, Albert W.; Rozet, J.P.; Tavernier, M.; Shafroth, S. M.; Krause, Manfred O.

doi:10.1088/0022-3700/9/7/006

Cited by 70 publications

(26 citation statements)

References 7 publications

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“…Coupling and relativity sensitively influence the electrons' wave functions and, through the wave functions' overlaps, also the DPI cross sections. For example, the K h 1 line originates in a transition requiring a spin flip, which is dipole forbidden in the pure LS coupling scheme, and becomes fully allowed only in the jj scheme [6,18]. Thus, its intensity and relative contribution to R K increase rapidly over the Z range addressed here as the coupling becomes more intermediate.…”

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confidence: 83%

Intrashell Electron-Interaction-Mediated Photoformation of Hollow Atoms near Threshold

et al. 2008

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Double photoionization (DPI) of an atom by a single photon is a direct consequence of electron-electron interactions within the atom. We have measured the evolution of the K-shell DPI from threshold up in transition metals by high-resolution x-ray emission spectroscopy of the Kh alpha hypersatellites, photoexcited by monochromatized synchrotron radiation. The measured evolution of the single-to-double photoionization cross-section ratio with excitation energy was found to be universal. Theoretical fits suggest that near threshold DPI is predominantly a semiclassical knockout effect, rather than the purely quantum-mechanical shake-off observed at the infinite photon energy limit.

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confidence: 83%

Intrashell Electron-Interaction-Mediated Photoformation of Hollow Atoms near Threshold

et al. 2008

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“…The HS spectra of 3d transition elements have been studied experimentally reasonably well ͑although mostly with low resolution, as discussed in I͒, starting with the seminal measurements of Briand et al ͓9,10͔ and ending, for the present, with our preceding paper I. High-resolution measurements of HS spectra of the 4d elements are, however, much fewer. This is particularly true for studies employing the more controlled and less violent excitation methods by electrons and photons.…”

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confidence: 91%

K-shell diagram and hypersatellite spectra of4dtransition elements

et al. 2009

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The K-shell diagram ͑K␣ 1,2 and K␤ 1,3 ͒ and hypersatellite ͑HS͒ ͑K h ␣ 1,2 ͒ spectra of Y, Zr, Mo, and Pd have been measured with high energy-resolution using photoexcitation by 90 keV synchrotron radiation. Comparison of the measured and ab initio calculated HS spectra demonstrates the importance of quantum electrodynamical ͑QED͒ effects for the HS spectra. Phenomenological fits of the measured spectra by Voigt functions yield accurate values for the shift of the HS from the diagram lines, the splitting of the HS lines, and their intensity ratio. Good agreement with theory was found for all quantities except for the intensity ratio, which is dominated by the intermediacy of the coupling of the angular momenta. The observed deviations imply that our current understanding of the variation of the coupling scheme from LS to jj across the periodic table may require some revision.

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“…The step shown in the extracted background is 163 ±5 eV above the L\\\ edge. The Z+l model [14], i.e., using the x-ray atomic-energy level [16] of Bi to calculate the energy of the second core hole, gives 161.9 ±0.5 eV and 157.4 ±0.6 eV for the A^vi and A^vii levels, respectively. Therefore, it is clear that the step corresponds to a 1/?3/24/5/2(4/7/2) doubleelectron ionization.…”

Section: ^O(e)=^(e)/l\-^xc(e)]mentioning

confidence: 99%

“…We have now extended that analysis slightly to remove most of the XAFS structure in the absorption-edge data so that the multielectron features are more clearly revealed. For all the edges studied below, we compare the position of the step to that predicted by the Z+1 model [14], which appears to work well for deep atomic levels [2,6,8,9]. The x-ray-absorption data were collected on the wiggler beam line IV-1 at the Stanford Synchrotron Radiation Laboratory using Si(220) monochromator crystals, detuned 50% to reduce the harmonic content.…”

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Multielectron x-ray photoexcitation observations in x-ray-absorption fine-structure background

1992

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Multielectron excitations involving deep and shallow core levels have been identified for the first time in the x-ray-absorption fine-structure (XAFS) energy range for crystalline samples, RbBr and ;3-Pb02. The XAFS oscillations have been fitted and subtracted from the experimental data using theoretical standards. The positions of steps in the extracted background are in excellent agreement with the Z-h 1 approximation. The ability to determine this structure has important implications for XAFS and multiexcitation studies.PACS numbers: 78.70.Dm, 32.30.Rj, 32.80.Fb, 6l.lO.Lx Multielectron excitations in the x-ray absorption above K and L edges have been studied for a number of systems [1-11] and are important probes of the internal structure of the atoms. It is well known that such processes contribute significantly to the near-edge structure in absorption spectroscopy (often referred to as shake-up or shake-oflf processes), in the range 0-50 eV above an absorption edge. It is, however, less well known that multielectron features can exist at energies far above the edge, although they have been identified in a few special cases [1-10]. In particular they occur in the energy range 50 to approximately 1000 eV [6-10], the energy range commonly known as the XAFS (x-ray-absorption fine structure) region. In the XAFS data analysis, the XAFS oscillations are usually extracted assuming that the background is a smooth function that can be well approximated by an wth-order polynomial («, typically 4-8) or a multiple-spline (3-6 splines) fit. When small steps occur in the background, they introduce errors [6-10] in the XAFS oscillations extracted following this standard procedure.

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The structure of Kα hypersatellite spectra of Cu, Ni and Fe as a test of intermediate coupling

Cited by 70 publications

References 7 publications

Intrashell Electron-Interaction-Mediated Photoformation of Hollow Atoms near Threshold

Intrashell Electron-Interaction-Mediated Photoformation of Hollow Atoms near Threshold

K-shell diagram and hypersatellite spectra of4dtransition elements

Multielectron x-ray photoexcitation observations in x-ray-absorption fine-structure background

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