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Abstract
In this study we have investigated the influence of hydrogen intercalation on the local atomic structure of rhenium trioxide using a new approach to EXAFS data analysis, based on the evolutionary algorithm (EA). The proposed EA-EXAFS method is an extension of the conventional reverse Monte Carlo approach but is computationally more efficient. It allows one to perform accurate analysis of EXAFS data from distant coordination shells, taking into account both multiple-scattering and disorder (thermal and static) effects. The power of the EA-EXAFS method is first demonstrated on an example of the model system, pure ReO3, and then it is applied to an in situ study of hydrogen bronze HxReO3 upon hydrogen intercalation. The obtained results allow us to detect changes in the lattice dynamics and correlation of atomic motion, and to follow the structural development at different stages of the reaction.
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Affiliation(s)
- J Timoshenko
- Institute of Solid State Physics, University of Latvia, Kengaraga street 8, LV-1063 Riga, Latvia
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Agondanou JH, Nicolis I, Curis E, Purans J, Spyroulias GA, Coutsolelos AG, Bénazeth S. Correction to Gadolinium Acetylacetonate Tetraphenyl Monoporphyrinate Complex and Some of Its Derivatives: EXAFS Study and Molecular Dynamics Simulation. Inorg Chem 2013. [DOI: 10.1021/ic4023807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Purans J, Timoshenko J, Kuzmin A, Dalba G, Fornasini P, Grisenti R, Afify ND, Rocca F, Panfilis SD, Ozhogin I, Tiutiunnikov SI. Femtometer accuracy EXAFS measurements: Isotopic effect in the first, second and third coordination shells of germanium. ACTA ACUST UNITED AC 2009. [DOI: 10.1088/1742-6596/190/1/012063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Larcheri S, Rocca F, Pailharey D, Jandard F, Graziola R, Kuzmin A, Kalendarev R, Purans J. A new tool for nanoscale X-ray absorption spectroscopy and element-specific SNOM microscopy. Micron 2009; 40:61-5. [DOI: 10.1016/j.micron.2008.01.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 12/19/2007] [Accepted: 01/28/2008] [Indexed: 11/26/2022]
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Purans J, Afify ND, Dalba G, Grisenti R, De Panfilis S, Kuzmin A, Ozhogin VI, Rocca F, Sanson A, Tiutiunnikov SI, Fornasini P. Isotopic effect in extended x-ray-absorption fine structure of germanium. Phys Rev Lett 2008; 100:055901. [PMID: 18352392 DOI: 10.1103/physrevlett.100.055901] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Indexed: 05/26/2023]
Abstract
Extended x-ray absorption fine structure has been measured on two powdered samples of (70)Ge and (76)Ge as a function of temperature from 20 to 300 K. The effect of isotopic mass difference on the amplitude of relative atomic vibrations is neatly evidenced by the temperature dependence of the difference of Debye-Waller factors. The isotopic effect is also detected on the difference of nearest-neighbor average ineratomic distances, thanks to a resolution better than 10 fm.
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Affiliation(s)
- J Purans
- Dipartimento di Fisica, Università degli Studi di Trento, I-38050 Povo (Trento), Italy.
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Agondanou JH, Nicolis I, Curis E, Purans J, Spyroulias GA, Coutsolelos AG, Bénazeth S. Gadolinium Acetylacetonate Tetraphenyl Monoporphyrinate Complex and Some of Its Derivatives: EXAFS Study and Molecular Dynamics Simulation. Inorg Chem 2007; 46:6871-9. [PMID: 17658869 DOI: 10.1021/ic061861x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Many attempts to obtain single crystals appropriate for X-ray diffraction analysis of the Ln(tpp)(acac) derivatives (where Ln = Gd or Sm, tpp = tetraphenylporphyrin and acac = acetylacetonate) have failed so far. A suitable way to get structural parameters for these monoporphyrinates is to use extended X-ray absorption fine structure (EXAFS) spectroscopy. We recorded spectra of the monoporphyrins, Ln(tpp)(acac) and Gd(tpyp)(acac) (where tpyp = tetrapyridylporphyrin), and the bisporphyrin GdH(tpyp)2 in the solid state. We particularly focused our structural analysis on Gd(tpp)(acac), applying both molecular modeling and EXAFS, which allowed us to get accurate results about the local environment of the central atom. The Gd3+ ion of the complex at room temperature was found to be bonded to four monoporphyrin nitrogen atoms at an average distance R(Gd-N(av)) = 2.48 A and to three or four oxygen atoms at R(Gd-O(ac,w)) = 2.38 A from an acetylacetonato anion and a water molecule. The presence of the second water molecule in the coordination sphere was barely discernible by EXAFS analysis. Molecular modeling has provided further information about the coordination core geometry of the Gd(tpp)(acac) monoporphyrinate, including a bishydrated coordination sphere. Also, it has enabled the construction of a 3D structural model on which multiple scattering analyses were attempted. Monte Carlo simulation was used to validate the adjustments. EXAFS spectra analysis was carried out on the derivatives, displaying slight distortions in the lanthanide central-atom coordination geometry.
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Affiliation(s)
- J H Agondanou
- Laboratoire de biomathématiques, Faculté de pharmacie, Université Paris Descartes, 75006 Paris, France
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Merkle R, Vracar M, Kuzmin A, Purans J, Kotomin EA, Maier J. SrFexTi1−xO3−δ: studies of local structure and (electro)chemical oxygen incorporation kinetics. Z Anorg Allg Chem 2006. [DOI: 10.1002/zaac.200670063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Extended X-ray absorption fine structure (EXAFS) has been utilized to investigate the local atomic structure around Th, U, and Pu atoms in polycrystalline mixed dioxides Th(1-x)M(x)O2 (with M = U, Pu) for x ranging from 0 to 1. The composition dependence of the two first-coordination-shell distances was measured throughout the entire composition range for both solid solutions. The first-shell distances vary slightly across the solid-solution composition with values close to those of the pure dioxide parents, indicating a bimodal cation-oxygen distribution. In contrast, the second-shell distance varies strongly with composition, with values close to the weighted amount average distances. Nevertheless, in both systems, the lattice cell parameters, deduced from the first- and second-shell bond determined by EXAFS, are very close to those measured from X-ray diffraction (XRD). They vary linearly with composition, accurately following Vegard's law.
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Affiliation(s)
- S Hubert
- Institut de Physique Nucléaire, Université Paris Sud, 91406-Orsay, France.
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Purans J, Fourest B, Cannes C, Sladkov V, David F, Venault L, Lecomte M. Structural Investigation of Pd(II) in Concentrated Nitric and Perchloric Acid Solutions by XAFS. J Phys Chem B 2005; 109:11074-82. [PMID: 16852349 DOI: 10.1021/jp045489n] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
XAFS spectra of palladium(II) in concentrated HNO3/HClO4 acid mixtures have been recorded and analyzed. Structural parameters of the Pd(H2O)4(2+) complex and the mixed nitric Pd(NO3)2(H2O)2 complex, for the first time, were determined by the XAFS method. For pure 5 M HClO4 and for mixtures (0-0.3 M HNO3), the XAFS spectra of the 0.02 M Pd solutions are indeed very similar and originated from four Pd-O(w) equivalent distances. For the Pd(H2O)4(2+) square-planar aqua ion in strong perchloric acid, the use of an FEFF6 theoretical approach led to a first-shell Pd-O(w) distance of 2.00 (1) A and a Debye-Waller (DW) factor of sigma2 = 0.0030 (3) A2. Four water molecules are tightly bound to the Pd2+ ion in the equatorial plane, while two (or one) axial water molecules are weakly bound to the metal ion at 2.5 A with a DW factor of 0.015 (5) A2. For highly concentrated mixtures (4-6 M HNO3) and for pure concentrated (4-6 M) nitric acid as well as for crystalline powder Pd(NO3)2(H2O)2, the XAFS spectra are very similar and are determined by the mixed nitric complex Pd(NO3)2(H2O)2: four Pd-O near-equivalent distances of 2.01 (1) A from two H2O and two NO3 molecules with a total DW factor of sigma2 = 0.0037 (3) A2. Moreover, two Pd---N distances of 2.8-2.9 A were determined in the second coordination shell. Finally, for intermediate mixtures (1-3 M HNO3 in 5 M HClO4), the XAFS spectra are a superposition of the XAFS of Pd(H2O)4(2+) and Pd(NO3)2(H2O)2 complexes. The mean ligand number NO3(-) around Pd2+ has been calculated, and the XAFS results at pH close to zero confirm the spectrophotometric results previously published.
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Affiliation(s)
- J Purans
- Institut de Physique Nucléaire, 91406 Orsay Cedex, France.
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Affiliation(s)
- A. Kuzmin
- Institute of Solid State Physics, University of Latvia, Kengaraga street 8, 1063 Riga, Latvia
| | - J. Purans
- Institute of Solid State Physics, University of Latvia, Kengaraga street 8, 1063 Riga, Latvia
- Dipartimento di Fisica, Università di Trento, Povo (Trento) 38050, Italy
| | - R. Kalendarev
- Institute of Solid State Physics, University of Latvia, Kengaraga street 8, 1063 Riga, Latvia
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Agondanou JH, Spyroulias GA, Purans J, Tsikalas G, Souleau C, Coutsolelos AG, Bénazeth S. XAFS study of gadolinium and samarium bisporphyrinate complexes. Inorg Chem 2001; 40:6088-96. [PMID: 11703105 DOI: 10.1021/ic000410o] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The comparative X-ray absorption spectroscopy study of gadolinium and samarium bisporphyrinate complexes represented by the formulas Gd(III)H(oep)(tpp), Gd(III)(oep)(2), Gd(III)H(tpp)(2) and Sm(III)H(oep)(tpp), Sm(III)(oep)(2), Sm(III)H(tpp)(2) is reported. The XAFS spectra are recorded on the LURE-DCI storage ring (Orsay, France) in transmission mode on the microcrystalline samples at the Gd and Sm L(3) edges. The local environment for Ln(3+) ions has been reconstructed applying one-shell and two-shell XAFS analysis procedures. The protonated and nonprotonated bisporphyrinate complexes present different XAFS features. After our analysis on the title derivatives, the gadolinium ion (at 80 K) is found to be bonded: (i) to eight nitrogen atoms at R(Gd-N) 2.50 A, for Gd(III)(oep)(2) [Debye-Waller (DW) factor 0.004 A(2)]; (ii) to seven nitrogen atoms at R(Gd-N) 2.49 A, for Gd(III)H(oep)(tpp) [DW factor 0.005 A(2)] and one nitrogen at long distance; and (iii) to six nitrogen atoms at R(Gd-N) 2.50 A [DW factor 0.006 A(2)] and two nitrogen atoms at long distance for Gd(III)H(tpp)(2). A similar coordination sphere has been detected for the corresponding Sm derivatives. So, the samarium ion (at room temperature) is bonded: (i) to eight nitrogen atoms at R(Sm-N) 2.53 A, for Sm(III)(oep)(2) [DW factor 0.006 A(2)]; (ii) to seven nitrogen atoms at R(Sm-N) 2.53 A, for Sm(III)H(oep)(tpp) [DW factor 0.006 A(2)] and one nitrogen at long distance; and (iii) to six nitrogen atoms at R(Sm-N) 2.50 A, for Sm(III)H(tpp)(2) [DW factor 0.006 A(2)] and two nitrogen atoms at long distance. As far as concerns Ln(III)(oep)(2) complexes, the increase of Ln-N distance in the series Gd(3+) < Eu(3+) < Sm(3+) reflects an increase in the ionic radii, which are in good agreement with previously published XRD data on Eu(III)(oep)(2). Moreover, the protonated Ln(III)H(oep)(tpp) and Ln(III)H(tpp)(2) complexes possess systematically shorter distances of about 0.02 A between the XAFS and XRD data. This difference is attributed to the asymmetry of the distribution concerning Ln-N distances.
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Affiliation(s)
- J H Agondanou
- Laboratoire de Chimie Physique Minérale et Bioinorganique, EA401, UFR Pharmacie, Université Paris XI, 92296 Paris, France
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Kuzmin A, Purans J, Kalendarev R, Pailharey D, Mathey Y. XAS, XRD, AFM and Raman studies of nickel tungstate electrochromic thin films. Electrochim Acta 2001. [DOI: 10.1016/s0013-4686(01)00365-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Purans J, Kuzmin A, Parent P, Laffon C. X-ray absorption study of the electronic structure of tungsten and molybdenum oxides on the O K-edge. Electrochim Acta 2001. [DOI: 10.1016/s0013-4686(01)00370-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Menushenkov AP, Klementev KV, Cortes R, Purans J. Lattice softening in superconducting compositions of Ba(K)BiO3. J Synchrotron Radiat 2001; 8:845-847. [PMID: 11512952 DOI: 10.1107/s0909049501000115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2000] [Accepted: 12/20/2000] [Indexed: 05/23/2023]
Abstract
Temperature dependent x-ray absorption spectra investigation were measured for Ba(1-x)K(x)BiO3 (Bi L3-edge) with x =0.0, 0.25, 0.4, 0.5 and for BaPbO3 (Pb L3-edge). It was found that at low temperatures the Debye-Waller factor of the square diagonal Bi-Bi bond has the maximum value near the insulator-metal phase transition for the compound with x = 0.25 and x = 0.4. Temperature dependence of the Debye-Waller factor of Bi-Bi bond strongly differs from the Einstein model curve that well describes the harmonic systems (for example BaPbO3). This behavior is consistent with the strong anharmonicity of the Bi-O shell due to the double-well vibration potential reported by us earlier. Presented results point to the essential lattice softening of the superconducting compositions, which is important for the understanding of superconductivity mechanism in perovskite type oxides.
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Dalba G, Fornasini P, Grisenti R, Purans J. Anharmonicity and thermal expansion in crystalline germanium. J Synchrotron Radiat 1999; 6:253-254. [PMID: 15263268 DOI: 10.1107/s0909049598017105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/1998] [Accepted: 12/09/1998] [Indexed: 05/24/2023]
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Kuzmin A, Purans J. X-Ray Absorption Study of the Short Range Order of Tungsten and Molybdenum Ions in BaO-P2O5-WO3and CaO-P2O5-MoO3Glasses. ACTA ACUST UNITED AC 1997. [DOI: 10.1051/jp4:19972105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Rocca F, Kuzmin A, Purans J, Mariotto G. X-ray-absorption spectroscopy of Nd3+-exchanged beta -alumina crystal. Phys Rev B Condens Matter 1996; 53:11444-11450. [PMID: 9982762 DOI: 10.1103/physrevb.53.11444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Rocca F, Kuzmin A, Purans J, Mariotto G. X-ray-absorption spectroscopy of a Nd3+-exchanged beta "-alumina crystal. Phys Rev B Condens Matter 1994; 50:6662-6672. [PMID: 9974619 DOI: 10.1103/physrevb.50.6662] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Kuzmin A, Purans J, Benfatto M, Natoli CR. X-ray-absorption study of rhenium L3 and L1 edges in ReO3: Multiple-scattering approach. Phys Rev B Condens Matter 1993; 47:2480-2486. [PMID: 10006298 DOI: 10.1103/physrevb.47.2480] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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