Structure determination using EXAFS in real space: Ge

Hayes, T. M.; Sen, Parongama; Hunter, S. H.

doi:10.1088/0022-3719/9/24/006

Cited by 51 publications

(6 citation statements)

References 8 publications

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“…filter (window) (Hayes et al, 1976;Eisenberger and Kincaid, 1978) around one of the peaks (see dotted line in Fig. 2c), a particular coordination shell can be isolated and backtransformed into k-space ( Fig.…”

Section: Biophysical Journal Volume 37 1982mentioning

confidence: 99%

The electronic structure of Fe2+ in reaction centers from Rhodopseudomonas sphaeroides. II. Extended x-ray fine structure studies

Eisenberger¹,

Okamura²,

Fehér³

1982

Biophysical Journal

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Extended x-ray absorption fine structure (EXAFS) studies were performed on reaction centers (RC) of the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26. RC containing two, one, and no quinones (2Q, 1Q, 0Q) samples were studied. The average ligand distance of the first coordination shell was determined to be 2.10 +/- 0.02 A with a more distant shell at 4.14 +/- 0.05 A. The Fe2+ site in RC was found to have a very large structural disorder parameter, from which a spread in ligand distance per iron site of approximately +/- 0.1 A was deduced. The most likely coordination number of the first shell is six, with a mixture of oxygens and nitrogens as ligands. The edge absorption results are consistent with the Fe2+ being in distorted octahedral environment. The EXAFS spectra of the 2Q and 1Q samples with and without O-phenanthroline were found to be the same. This indicates that either the secondary quinone and o-phenanthroline do not bind to Fe2+ or that they replace an equivalent ligand. The 0Q sample showed a 12% decrease in the EXAFS amplitude, which was restored upon addition of o-phenanthroline. These results can be explained by either a loss of a ligand or a severe conformational change when the primary quinone was removed.

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Section: Biophysical Journal Volume 37 1982mentioning

confidence: 99%

The electronic structure of Fe2+ in reaction centers from Rhodopseudomonas sphaeroides. II. Extended x-ray fine structure studies

Eisenberger¹,

Okamura²,

Fehér³

1982

Biophysical Journal

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“…The NTE behavior of materials can be experimentally studied by means of Extended X-Ray Absorption Fine Structure (EXAFS) spectroscopy, which enables the measurement of local dynamics of the crystal lattice. [19][20][21][22] Quantities which can be obtained from EXAFS spectra are, for example, mean square displacements (MSD) and mean square relative displacements (MSRD). Consequently, EXAFS has also been used to study the NTE phenomenon.…”

Section: Introductionmentioning

confidence: 99%

Ab initiolattice dynamical studies of silicon clathrate frameworks and their negative thermal expansion

Härkönen

Karttunen

2014

Phys. Rev. B

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The thermal and lattice dynamical properties of seven silicon clathrate framework structures are investigated with ab initio density functional methods (frameworks I, II, IV, V, VII, VIII, and H). The negative thermal expansion (NTE) phenomenon is investigated by means of quasiharmonic approximation and applying it to equal time displacement correlation functions. The thermal properties of the studied clathrate frameworks, excluding the VII framework, resemble those of the crystalline silicon diamond structure. The clathrate framework VII was found to have anomalous NTE temperature range up to 300 K and it is suitable for further studies of the mechanisms of NTE. Investigation of the displacement correlation functions revealed that in NTE, the volume derivatives of the mean square displacements and mean square relative displacements of atoms behave similarly to the vibrational entropy volume derivatives and consequently to the coefficients of thermal expansion as a function of temperature. All studied clathrate frameworks, excluding the VII framework, possess a phonon band gap or even two in the case of the framework V.

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“…We see this in the Fourier component of x(k), which is (2k*r), whereas in diffraction experiments it is (q*r). The range of 2k in EXAFS experiments is less than twice that of q in diffraction experiments; 2.5 5 2k 5 30 A' whereas 0 5 q 5 15 A' [34]. This, therefore, renders the (k*r) factor to be slightly less than (q*r) and so the amount of information obtained from E M S is less than from diffraction.…”

Section: Exafs and Exelfsmentioning

confidence: 94%

Stability of Bulk Metallic Glass Structure. Final Report

Jain¹,

Williams²

2003

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Structure determination using EXAFS in real space: Ge

Cited by 51 publications

References 8 publications

The electronic structure of Fe2+ in reaction centers from Rhodopseudomonas sphaeroides. II. Extended x-ray fine structure studies

The electronic structure of Fe2+ in reaction centers from Rhodopseudomonas sphaeroides. II. Extended x-ray fine structure studies

Ab initiolattice dynamical studies of silicon clathrate frameworks and their negative thermal expansion

Stability of Bulk Metallic Glass Structure. Final Report

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