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Tantau LJ, Chantler CT, Bourke JD, Islam MT, Payne AT, Rae NA, Tran CQ. Structure determination from XAFS using high-accuracy measurements of x-ray mass attenuation coefficients of silver, 11 keV-28 keV, and development of an all-energies approach to local dynamical analysis of bond length, revealing variation of effective thermal contributions across the XAFS spectrum. J Phys Condens Matter 2015; 27:266301. [PMID: 26075571 DOI: 10.1088/0953-8984/27/26/266301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We use the x-ray extended range technique (XERT) to experimentally determine the mass attenuation coefficient of silver in the x-ray energy range 11 kev-28 kev including the silver K absorption edge. The results are accurate to better than 0.1%, permitting critical tests of atomic and solid state theory. This is one of the most accurate demonstrations of cross-platform accuracy in synchrotron studies thus far. We derive the mass absorption coefficients and the imaginary component of the form factor over this range. We apply conventional XAFS analytic techniques, extended to include error propagation and uncertainty, yielding bond lengths accurate to approximately 0.24% and thermal Debye-Waller parameters accurate to 30%. We then introduce the FDMX technique for accurate analysis of such data across the full XAFS spectrum, built on full-potential theory, yielding a bond length accuracy of order 0.1% and the demonstration that a single Debye parameter is inadequate and inconsistent across the XAFS range. Two effective Debye-Waller parameters are determined: a high-energy value based on the highly-correlated motion of bonded atoms (σ(DW) = 0.1413(21) Å), and an uncorrelated bulk value (σ(DW) = 0.1766(9) Å) in good agreement with that derived from (room-temperature) crystallography.
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Affiliation(s)
- L J Tantau
- School of Physics, University of Melbourne, Victoria 3010, Australia
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Chantler CT, Kinnane MN, Gillaspy JD, Hudson LT, Payne AT, Smale LF, Henins A, Pomeroy JM, Kimpton JA, Takacs E, Makonyi K. Chantler et al. reply. Phys Rev Lett 2013; 110:159302. [PMID: 25167322 DOI: 10.1103/physrevlett.110.159302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Indexed: 06/03/2023]
Affiliation(s)
- C T Chantler
- School of Physics, The University of Melbourne, Australia
| | - M N Kinnane
- School of Physics, The University of Melbourne, Australia and National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
| | - J D Gillaspy
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
| | - L T Hudson
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
| | - A T Payne
- School of Physics, The University of Melbourne, Australia
| | - L F Smale
- School of Physics, The University of Melbourne, Australia
| | - A Henins
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
| | - J M Pomeroy
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
| | - J A Kimpton
- School of Physics, The University of Melbourne, Australia and Australian Synchrotron, Melbourne, Victoria 3000, Australia
| | - E Takacs
- Experimental Physics Department, University of Debrecen, Bem ter 18/A, Debrecen 4028, Hungary
| | - K Makonyi
- National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA
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Chantler CT, Kinnane MN, Gillaspy JD, Hudson LT, Payne AT, Smale LF, Henins A, Pomeroy JM, Tan JN, Kimpton JA, Takacs E, Makonyi K. Testing three-body quantum electrodynamics with trapped Ti20+ ions: evidence for a Z-dependent divergence between experiment and calculation. Phys Rev Lett 2012; 109:153001. [PMID: 23102303 DOI: 10.1103/physrevlett.109.153001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Indexed: 06/01/2023]
Abstract
We report a new test of quantum electrodynamics (QED) for the w (1s2p(1)P(1)→1s(2)(1)S(0)) x-ray resonance line transition energy in heliumlike titanium. This measurement is one of few sensitive to two-electron QED contributions. Systematic errors such as Doppler shifts are minimized in our experiment by trapping and stripping Ti atoms in an electron beam ion trap and by applying absolute wavelength standards to calibrate the dispersion function of a curved-crystal spectrometer. We also report a more general systematic discrepancy between QED theory and experiment for the w transition energy in heliumlike ions for Z>20. When all of the data available in the literature for Z=16-92 are taken into account, the divergence is seen to grow as approximately Z(3) with a statistical significance on the coefficient that rises to the level of 5 standard deviations. Our result for titanium alone, 4749.85(7) eV for the w line, deviates from the most recent ab initio prediction by 3 times our experimental uncertainty and by more than 10 times the currently estimated uncertainty in the theoretical prediction.
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Affiliation(s)
- C T Chantler
- School of Physics, The University of Melbourne, Parkville 3010, Australia.
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