Photoinduced Ferrimagnetic Systems in Prussian Blue Analogues CIxCo4[Fe(CN)6]y (CI = Alkali Cation). 2. X-ray Absorption Spectroscopy of the Metastable State

Moulin, Christophe; Villain, F.; Bleuzen, Anne; Arrio, § Marie-Anne; Sainctavit, Philippe; Lomenech, Claire; Escax, Virginie; Baudelet, F.; Dartyge, E.; Gallet, Jean‐Jacques; Verdaguer, Michel

doi:10.1021/ja000349m

Cited by 213 publications

(261 citation statements)

References 25 publications

(47 reference statements)

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“…56,66 To simulate the spectra, the Slater-Condon-Shortley parameters (F i and G i ) were first reduced to 80% of their HartreeFock calculated values to account for the over-estimation of electron-electron repulsion found in calculations of the free ion, i.e (κ=0.8) in nomenclature used elsewhere. [56][57][58] The spectrum is calculated from the sum of all possible transitions for an electron excited from the 2p level into a 3d level. 67 (D 4h ).…”

Section: Xas Data Collection and Reductionmentioning

confidence: 99%

Fe L-Edge X-ray Absorption Spectroscopy of Low-Spin Heme Relative to Non-heme Fe Complexes: Delocalization of Fe d-Electrons into the Porphyrin Ligand

et al. 2006

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Hemes (iron porphyrins) are involved in a range of functions in biology including electron transfer, small molecule binding and transport, and O 2 activation. The delocalization of the Fe d-electrons into the porphyrin ring and its effect on the redox chemistry and reactivity of these systems has been difficult to study by optical spectroscopies due to the dominant porphyrin π → π* transitions which obscure the metal center. Recently we have developed a methodology that allows for the interpretation of the multiplet structure of Fe L-edges in terms of differential orbital covalency (i.e. differences in mixing of the d-orbitals with ligand orbitals) using a valence bond configuration interaction (VBCI) model. Applied to low spin heme systems, this methodology allows experimental determination of the delocalization of the Fe d-electrons into the porphyrin (p) ring both in terms of P→Fe σ and π donation and Fe→P π back-bonding. We find that π donation to Fe(III) is much larger than π back-bonding from Fe(II), indicating that a hole super-exchange pathway dominates electron transfer. The implications of the results are also discussed in terms of the differences between heme and non-heme oxygen activation chemistry.

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Section: Xas Data Collection and Reductionmentioning

confidence: 99%

Fe L-Edge X-ray Absorption Spectroscopy of Low-Spin Heme Relative to Non-heme Fe Complexes: Delocalization of Fe d-Electrons into the Porphyrin Ligand

et al. 2006

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“…44, 45 Arrio and co-workers have analyzed a number of cubic systems with CNligands bridging two transition metal sites. [41][42][43]46 It was found for the Cr sites of these compounds that the LMCT model could not reproduce the shape of the spectra, and the multiplet model was adapted to include the effects of MLCT, which successfully reproduced the spectral shapes.…”

Section: Introductionmentioning

confidence: 99%

Fe L-Edge XAS Studies of K₄[Fe(CN)₆] and K₃[Fe(CN)₆]: A Direct Probe of Back-Bonding

et al. 2006

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Abstract:Distinct spectral features at the Fe L-edge of the two compounds K3[Fe(CN)6] and K4[Fe(CN)6] have been identified and characterized as arising from contributions of the ligand π* orbitals due to metalto-ligand back-bonding. In addition, the L-edge energy shifts and total intensities allow changes in the ligand field and effective nuclear charge to be determined. It is found that the ligand field term dominates the edge energy shift. The results of the experimental analysis were compared to BP86 DFT calculations. The overall agreement between the calculations and experiment is good; however, a larger difference in the amount of π back-donation between Fe(II) and Fe(III) is found experimentally. The analysis of L-edge spectral shape, energy shift, and total intensity demonstrates that Fe L-edge X-ray absorption spectroscopy provides a direct probe of metal-to-ligand back-bonding.

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“…[36][37][38][39][40][41] Adsorption/desorption of hydroxyls produces the moment variation for our Ti oxide clusters. Adsorption/ desorption of water molecules give rise to the moment variation for molecular magnets.…”

Section: Summary Of Dft Calculationsmentioning

confidence: 94%

Experimental and theoretical studies of hydroxyl-induced magnetism in TiO nanoclusters

et al. 2012

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A main challenge in understanding the defect ferromagnetism in dilute magnetic oxides is the direct experimental verification of the presence of a particular kind of defect and distinguishing its magnetic contributions from other defects. The magnetic effect of hydroxyls on TiO nanoclusters has been studied by measuring the evolution of the magnetic moment as a function of moisture exposure time, which increases the hydroxyl concentration. Our combined experiment and density-functional theory (DFT) calculations show that as dissociative water adsorption transforms oxygen vacancies into hydroxyls, the magnetic moment shows a significant increase. DFT calculations show that the magnetic moment created by hydroxyls arises from 3d orbitals of neighboring Ti sites predominantly from the top and second monolayers. The two nonequivalent hydroxyls contribute differently to the magnetic moment, which decreases as the separation of hydroxyls increases. This work illustrates the essential interplay among defect structure, local structural relaxation, charge redistribution, and magnetism. The microscopic differentiation and clarification of the specific roles of each kind of intrinsic defect is critical for the future applications of dilute magnetic oxides in spintronic or other multifunctional materials.

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Photoinduced Ferrimagnetic Systems in Prussian Blue Analogues C^I_xCo₄[Fe(CN)₆]_y (C^I = Alkali Cation). 2. X-ray Absorption Spectroscopy of the Metastable State

Cited by 213 publications

References 25 publications

Fe L-Edge X-ray Absorption Spectroscopy of Low-Spin Heme Relative to Non-heme Fe Complexes: Delocalization of Fe d-Electrons into the Porphyrin Ligand

Fe L-Edge X-ray Absorption Spectroscopy of Low-Spin Heme Relative to Non-heme Fe Complexes: Delocalization of Fe d-Electrons into the Porphyrin Ligand

Fe L-Edge XAS Studies of K₄[Fe(CN)₆] and K₃[Fe(CN)₆]: A Direct Probe of Back-Bonding

Experimental and theoretical studies of hydroxyl-induced magnetism in TiO nanoclusters

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Photoinduced Ferrimagnetic Systems in Prussian Blue Analogues CIxCo4[Fe(CN)6]y (CI = Alkali Cation). 2. X-ray Absorption Spectroscopy of the Metastable State

Cited by 213 publications

References 25 publications

Fe L-Edge X-ray Absorption Spectroscopy of Low-Spin Heme Relative to Non-heme Fe Complexes: Delocalization of Fe d-Electrons into the Porphyrin Ligand

Fe L-Edge X-ray Absorption Spectroscopy of Low-Spin Heme Relative to Non-heme Fe Complexes: Delocalization of Fe d-Electrons into the Porphyrin Ligand

Fe L-Edge XAS Studies of K4[Fe(CN)6] and K3[Fe(CN)6]: A Direct Probe of Back-Bonding

Experimental and theoretical studies of hydroxyl-induced magnetism in TiO nanoclusters

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Photoinduced Ferrimagnetic Systems in Prussian Blue Analogues C^I_xCo₄[Fe(CN)₆]_y (C^I = Alkali Cation). 2. X-ray Absorption Spectroscopy of the Metastable State

Fe L-Edge XAS Studies of K₄[Fe(CN)₆] and K₃[Fe(CN)₆]: A Direct Probe of Back-Bonding