Fluorescence detection of exafs: Sensitivity enhancement for dilute species and thin films

Jaklevic, J.M.; Kirby, J. A.; Klein, Melvin P.; Robertson, Alan; Brown, G. S.; Eisenberger, P.

doi:10.1016/0038-1098(77)90548-8

Cited by 434 publications

(168 citation statements)

References 5 publications

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“…A 13-element Ge solid-state detector (Canberra Instruments) was used 24 to detect the Mn fluorescence signal. 25 We set different SCA windows for the each of the three concentric circles of detector elements, with shaping times of 1, 0.75, and 0.5 μs, based on the total number of counts each channel detects. The shaping time for the center channel, which "sees" the fewest total counts, is set at 1.0 μs, and for the outer channels that detect more total counts, because of increased scatter, the shaping time was set at 0.5 μs.…”

Section: X-ray Absorption Measurementsmentioning

confidence: 99%

Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

et al. 2000

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The oxygen-evolving complex of Photosystem II in plants and cyanobacteria catalyzes the oxidation of two water molecules to one molecule of dioxygen. A tetranuclear Mn complex is believed to cycle through five intermediate states (S 0 -S 4 ) to couple the four-electron oxidation of water with the one-electron photochemistry occurring at the Photosystem II reaction center. We have used X-ray absorption spectroscopy to study the local structure of the Mn complex and have proposed a model for it, based on studies of the Mn K-edges and the extended X-ray absorption fine structure of the S 1 and S 2 states. The proposed model consists of two di-μ-oxo-bridged binuclear Mn units with Mn-Mn distances of ~2.7 Å that are linked to each other by a mono-μ-oxo bridge with a Mn-Mn separation of ~3.3 Å. The Mn-Mn distances are invariant in the native S 1 and S 2 states. This report describes the application of X-ray absorption spectroscopy to S 3 samples created under physiological conditions with saturating flash illumination. Significant changes are observed in the Mn-Mn distances in the S 3 state compared to the S 1 and the S 2 states. The two 2.7 Å Mn-Mn distances that characterize the di-μ-oxo centers in the S 1 and S 2 states are lengthened to ~2.8 and 3.0 Å in the S 3 state, respectively. The 3.3 Å Mn-Mn and Mn-Ca distances also increase by 0.04-0.2 Å. These changes in Mn-Mn distances are interpreted as consequences of the onset of substrate/water oxidation in the S 3 state. Mn-centered oxidation is evident during the S 0 →S 1 and S 1 →S 2 transitions. We propose that the changes in Mn-Mn distances during the S 2 →S 3 transition are the result of ligand or water oxidation, leading to the Supporting Information Available: E-space S 3 state EXAFS spectrum; the data in k-space and the background that was removed to reduce the low-frequency contributions that show up as peaks at <1 Å in the Fourier transform; and the Fourier isolate of the k-space S 3 spectrum, shown overplotted on the S 3 EXAFS spectrum (PDF). This material is available free of charge via the Internet at http:// pubs.acs.org. NIH Public Access

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Section: X-ray Absorption Measurementsmentioning

confidence: 99%

Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

et al. 2000

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“…The 2p x-ray absorption spectra (L 2,3 edges) of 3d transition metal systems are generally measured with electron yield (EY) and fluorescence yield (FY) measurements detection 1 . Transmission measurements are less often applied because the strong absorption cross sections imply the need of a uniform sample thickness below in the order of 1 micron 2,3 .…”

Section: Introductionmentioning

confidence: 99%

Intrinsic deviations in fluorescence yield detected x-ray absorption spectroscopy: the case of the transition metal L_2,3edges

Kurian

Kunnus

Wernet

et al. 2012

J. Phys.: Condens. Matter

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Fluorescence yield (FY) detected x-ray absorption spectrum spectra (XAS) of 3d transition metal ions are calculated from the integrated 2p3d resonant x-ray emission spectrum. The resulting FY-XAS spectra are compared with the normal XAS spectra corresponding to the absorption cross section and significant deviations between both spectra are found. This implies that the assumption that the FY-XAS spectrum identifies with the XAS spectrum is disproved. Especially for the early transition metal systems the differences between FY-XAS and XAS are large, due to the opening of inelastic decay channels from selected x-ray absorption final states. The theoretical calculations show that the difference between FY detection and XAS is largest for the detection in depolarized geometry. The calculations are compared with experimental spectra for oxides and coordination compounds for Fe 2+ , Co 2+ and Ni 2+ systems. The implications for the sum rules in XAS and magnetic circular dichroism experiments are discussed.

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“…The O K and Cu L 2;3 XAS spectra were normalized to the beam current. In addition, the O K data have been corrected for the energy-dependent incident X-ray flux and for self-absorption effects according to a procedure described elsewhere [20,21].…”

Section: Methodsmentioning

confidence: 99%

The distribution of the doped holes in La2−xSrxCu1−yRuyO4−δ

Golden

Ebbinghaus

et al. 2002

Chemical Physics

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We present a systematic study of the perovskite-related system La 2Àx Sr x Cu 1Ày Ru y O 4Àd using Cu L 2;3 ; Ru L 2;3 , and O K X-ray absorption spectroscopy (XAS), magnetic and electrical measurements. This system can be regarded as hole-doped via substitution of La by Sr and to be electron-doped via substitution of Ru by Cu, and thus the question as to the distribution of the charge carriers and the interaction between Cu and Ru ions are central to our understanding of these novel systems. The comparison of the experimental data with the crystal-field-multiplet calculations shows clearly that the charge balance for x=2y > 1 is predominantly achieved by an increase of the Ru valence from Ru(IV) to Ru(V), while Cu remains in the Cu(II) oxidation state. Ó

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Fluorescence detection of exafs: Sensitivity enhancement for dilute species and thin films

Cited by 434 publications

References 5 publications

Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

Intrinsic deviations in fluorescence yield detected x-ray absorption spectroscopy: the case of the transition metal L_2,3edges

The distribution of the doped holes in La2−xSrxCu1−yRuyO4−δ

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Fluorescence detection of exafs: Sensitivity enhancement for dilute species and thin films

Cited by 434 publications

References 5 publications

Structural Change of the Mn Cluster during the S2→S3 State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

Structural Change of the Mn Cluster during the S2→S3 State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

Intrinsic deviations in fluorescence yield detected x-ray absorption spectroscopy: the case of the transition metal L2,3edges

The distribution of the doped holes in La2−xSrxCu1−yRuyO4−δ

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Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

Structural Change of the Mn Cluster during the S₂→S₃ State Transition of the Oxygen-Evolving Complex of Photosystem II. Does It Reflect the Onset of Water/Substrate Oxidation? Determination by Mn X-ray Absorption Spectroscopy

Intrinsic deviations in fluorescence yield detected x-ray absorption spectroscopy: the case of the transition metal L_2,3edges