Multiple-scattering regime and higher-order correlations in x-ray-absorption spectra of liquid solutions

Benfatto, M.; Natoli, C. R.; Bianconi, A.; García, J.; Marcelli, A.; Fanfoni, M.; Davoli, I.

doi:10.1103/physrevb.34.5774

Cited by 206 publications

(140 citation statements)

References 16 publications

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“…The main novelty of the theoretical approach implemented in MXAN lies in the fact that it provides the ''exact'' solution of the photoelectron Schrödinger problem by directly computing the inverse of the complete wave operator [24], instead of expanding the solution in powers of the free Green function, as is done, e.g., in the gnXAS analysis code [1,13,14]. In this way, all the MS contributions are automatically taken into account and the absorption coefficient is directly given as a function of the energy.…”

Section: Discussionmentioning

confidence: 99%

The role of Zn in the interplay among Langmuir–Blodgett multilayer and myelin basic protein: a quantitative analysis of XANES spectra

Benfatto

Longa

Qin

et al. 2004

Biophysical Chemistry

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Section: Discussionmentioning

confidence: 99%

The role of Zn in the interplay among Langmuir–Blodgett multilayer and myelin basic protein: a quantitative analysis of XANES spectra

Benfatto

Longa

Qin

et al. 2004

Biophysical Chemistry

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“…While this series is absolutely convergent for nonoverlapping MT spheres, provided the spectral radius of the matrix GT is less than one [38], it is known to diverge for the case of space-filling cells. This is easily seen by using the inequality (B.11) in Appendix B, putting l = l l max , whereby…”

Section: Convergence Of Full Potential Multiple Scattering Theorymentioning

confidence: 99%

“…Insertion of the expressions Eq.s (38) and (44) into the identity Eq. (32) provides a set of algebraic equations (known as MSE) that determine the expansion coefficients A j L (k) and the A o L (k) in such a way that the local representations are smoothly continuous across the common boundary of contiguous cells.…”

Section: Scattering Statesmentioning

confidence: 99%

Full-potential multiple scattering theory with space-filling cells for bound and continuum states

Hatada¹,

Hayakawa²,

Benfatto³

et al. 2010

J. Phys.: Condens. Matter

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Abstract. We present a rigorous derivation of a real space Full-Potential MultipleScattering-Theory (FP-MST) that is free from the drawbacks that up to now have impaired its development (in particular the need to expand cell shape functions in spherical harmonics and rectangular matrices), valid both for continuum and bound states, under conditions for space-partitioning that are not excessively restrictive and easily implemented. In this connection we give a new scheme to generate local basis functions for the truncated potential cells that is simple, fast, efficient, valid for any shape of the cell and reduces to the minimum the number of spherical harmonics in the expansion of the scattering wave function. The method also avoids the need for saturating 'internal sums' due to the re-expansion of the spherical Hankel functions around another point in space (usually another cell center). Thus this approach, provides a straightforward extension of MST in the Muffin-Tin (MT) approximation, with only one truncation parameter given by the classical relation l max = kR b , where k is the electron wave vector (either in the excited or ground state of the system under consideration) and R b the radius of the bounding sphere of the scattering cell. Moreover, the scattering path operator of the theory can be found in terms of an absolutely convergent procedure in the l max → ∞ limit. Consequently, this feature provides a firm ground to the use of FP-MST as a viable method for electronic structure calculations and makes possible the computation of x-ray spectroscopies, notably photo-electron diffraction, absorption and anomalous scattering among others, with the ease and versatility of the corresponding MT theory. Some numerical applications of the theory are presented, both for continuum and bound states.

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“…However, our attempts to obtain it were unsuccessful, and we always found a mixture of phases, including LuFe 2 O 4 , in our specimens. Since the main difference between XANES spectra of different ionic states with similar local structure geometry (that is the FeO 5 bipyramid) comes from the chemical shift of the absorption edge, being that their spectral shape is alike because it mainly depends on the local structural geometry [52], we have performed two simulations. The first one uses the XANES spectra of LuFeCoO 4 as reference for the hexagonal (space group R-3m) structure, while the second one makes use of the LuFe 2 O 4 XANES spectra.…”

Section: A Xanes Spectramentioning

confidence: 99%

Strong local lattice instability in hexagonal ferritesRFe2O4(R= Lu,Y,Yb) revealed by x-ray absorption spe

et al. 2014

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We present here an x-ray absorption study of the RFe 2 O 4 series (LuFe 2 O 4 , YFe 2 O 4 , YbFe 2 O 4 , and LuCoFeO 4 ) at the Fe K-edge. Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) spectra were measured at temperatures ranging from 100 K to 390 K crossing the charge ordering (CO) transition temperatures on both isotropic and oriented powder samples. Unpolarized and polarized x-ray absorption spectra with the x-ray polarization parallel and perpendicular to the hexagonal c axis were obtained separately. The XANES spectra show almost no dependence with either polarization or temperature. This indicates that, in contrast to its average crystallographic structure, the local electronic and geometrical state of the Fe atom is barely anisotropic, and it remains the same above and below the proposed CO. Moreover, the linear combination of two spectra corresponding to the pure ionic states Fe 2+ and Fe 3+ does not fit to the experimental XANES of either LuFe 2 O 4 , YFe 2 O 4 , or YbFe 2 O 4 , discarding total ionic segregation in favor of an intermediate mixed valence state. The maximum charge disproportionation compatible with the XANES spectra is 0.5 ± 0.1 electrons in the whole temperature range. The polarized EXAFS spectra have allowed us to analyze the local structure separating the different contributions mixed up in the polycrystal. Best-fit results show that the five oxygen atoms of the first coordination shell are at nearly the same distance but with a large Debye-Waller factor. Neither the interatomic distances nor the Debye-Waller factors of the first oxygen coordination shell change with temperature, indicating that the dynamical structural distortion of the high-temperature symmetric hexagonal phase freezes upon cooling down. Thus, the local structure instability of the mixed valence is in the origin of the structural transitions.

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Multiple-scattering regime and higher-order correlations in x-ray-absorption spectra of liquid solutions

Cited by 206 publications

References 16 publications

The role of Zn in the interplay among Langmuir–Blodgett multilayer and myelin basic protein: a quantitative analysis of XANES spectra

The role of Zn in the interplay among Langmuir–Blodgett multilayer and myelin basic protein: a quantitative analysis of XANES spectra

Full-potential multiple scattering theory with space-filling cells for bound and continuum states

Strong local lattice instability in hexagonal ferritesRFe2O4(R= Lu,Y,Yb) revealed by x-ray absorption spe

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