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Journal ArticleDOI

K{beta} resonant x-ray emission spectra in MnF{sub 2}

15 Jan 2000-Physical Review B (American Physical Society)-Vol. 61, Iss: 4, pp 2553-2560
TL;DR: In this article, experimental and theoretical results on Mn K{beta] resonant x-ray emission spectra (K{beta} RXES) at the pre-edge region of K-edge X-ray absorption spectroscopy in a powdered MnF{sub 2} sample were studied theoretically in terms of coherent second-order optical process, using a MnF {sub 6}{sup -4} cluster model with the effects of intra-atomic multiplet coupling and interatomic hybridization in the space of three configurations and taking into account both the Mn 1s-3d
Abstract: We report experimental and theoretical results on Mn K{beta} resonant x-ray emission spectra (K{beta} RXES) at the pre-edge region of K-edge x-ray absorption spectroscopy in a powdered MnF{sub 2} sample. The experimental results are studied theoretically in terms of coherent second-order optical process, using a MnF{sub 6}{sup -4} cluster model with the effects of intra-atomic multiplet coupling and interatomic hybridization in the space of three configurations and taking into account both the Mn 1s-3d quadrupole excitation and the Mn 1s-4p dipole excitation. The agreement between theory and experiment is good. Moreover, we show that if the sample is a single crystal the resonant x-ray emission spectroscopy caused by the quadrupole excitation has a strong sensitivity to the angle of the incident photon. (c) 2000 The American Physical Society.
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Journal ArticleDOI
TL;DR: In this article, the authors review recent developments in Kα and Kβ spectroscopy and show how the chemical sensitivity of the fluorescence lines can be exploited for selective X-ray absorption studies.

775 citations

Journal ArticleDOI
TL;DR: In this article, a review of electronic excitations in materials under extreme conditions using inelastic x-ray scattering (IXS) is presented, where the incident X-ray energy can easily be tuned to absorption edges, and resonant IXS is often employed.
Abstract: Investigating electronic structure and excitations under extreme conditions gives access to a rich variety of phenomena. High pressure typically induces behavior such as magnetic collapse and the insulator-metal transition in 3d transition metals compounds, valence fluctuations or Kondo-like characteristics in $f$-electron systems, and coordination and bonding changes in molecular solids and glasses. This article reviews research concerning electronic excitations in materials under extreme conditions using inelastic x-ray scattering (IXS). IXS is a spectroscopic probe of choice for this study because of its chemical and orbital selectivity and the richness of information it provides. Being an all-photon technique, IXS has a penetration depth compatible with high pressure requirements. Electronic transitions under pressure in 3d transition metals compounds and $f$-electron systems, most of them strongly correlated, are reviewed. Implications for geophysics are mentioned. Since the incident X-ray energy can easily be tuned to absorption edges, resonant IXS, often employed, is discussed at length. Finally studies involving local structure changes and electronic transitions under pressure in materials containing light elements are briefly reviewed.

141 citations

Journal ArticleDOI
TL;DR: The Kα RIXS approach can be used as a stand-alone method, in combination with L-edge XAS for strongly covalent systems that are difficult to probe by UV/vis spectroscopy, or as an extension to conventional absorption spectroscope for a wide range of transition metal enzymes and catalysts.
Abstract: Data from Kα resonant inelastic X-ray scattering (RIXS) have been used to extract electronic structure information, i.e., the covalency of metal–ligand bonds, for four iron complexes using an experimentally based theoretical model. Kα RIXS involves resonant 1s→3d excitation and detection of the 2p→1s (Kα) emission. This two-photon process reaches similar final states as single-photon L-edge (2p→3d) X-ray absorption spectroscopy (XAS), but involves only hard X-rays and can therefore be used to get high-resolution L-edge-like spectra for metal proteins, solution catalysts and their intermediates. To analyze the information content of Kα RIXS spectra, data have been collected for four characteristic σ-donor and π-back-donation complexes: ferrous tacn [FeII(tacn)2]Br2, ferrocyanide [FeII(CN)6]K4, ferric tacn [FeIII(tacn)2]Br3 and ferricyanide [FeIII(CN)6]K3. From these spectra metal–ligand covalencies can be extracted using a charge-transfer multiplet model, without previous information from the L-edge XAS experiment. A direct comparison of L-edge XAS and Kα RIXS spectra show that the latter reaches additional final states, e.g., when exciting into the eg (σ*) orbitals, and the splitting between final states of different symmetry provides an extra dimension that makes Kα RIXS a more sensitive probe of σ-bonding. Another key difference between L-edge XAS and Kα RIXS is the π-back-bonding features in ferro- and ferricyanide that are significantly more intense in L-edge XAS compared to Kα RIXS. This shows that two methods are complementary in assigning electronic structure. The Kα RIXS approach can thus be used as a stand-alone method, in combination with L-edge XAS for strongly covalent systems that are difficult to probe by UV/vis spectroscopy, or as an extension to conventional absorption spectroscopy for a wide range of transition metal enzymes and catalysts.

75 citations

Journal ArticleDOI
TL;DR: In this article, the 1s3p RIXS plane in hematite (Fe2O3) and anatase titania (TiO2) is analyzed and the core hole effect separates local and non-local excitations in titania.
Abstract: Some general aspects concerning resonant X-ray spectroscopy are discussed and an analysis of the 1s3p RIXS plane in hematite (Fe2O3) and anatase titania (TiO2) is presented. We emphasize the importance of recording a full RIXS plane as opposed to line scans. In a simple system such as hematite it is possible to assign the K absorption pre-edge features to ligand field split orbitals and non-local excitations using spin-selective spectroscopy. The core hole effect separates local and non-local excitations in titania.

71 citations

Journal ArticleDOI
TL;DR: A review of the electronic, magnetic and spectroscopic properties of manganese (Mn)-based nanostructures is presented in this paper, where a general overview of various kinds of Mn structures as well as several theoretical methods with their own limitations are presented.
Abstract: This paper presents a review of the electronic, magnetic and spectroscopic properties of manganese (Mn)-based nanostructures. In the last few years a variety of techniques have been used to prepare mesoscopic transition-metal islands and novel effects associated with the electronic structure in nanoscale systems have been reported. Mn in the atomic configuration possesses a moment as high as 5μB so it should be very interesting to dope semiconductors with Mn for spin injection or to use Mn itself for permanent magnets. In this paper the introduction (section 1) focuses mainly on metallic Mn nanostructures which are the core of this review. Nevertheless we try to present a general overview of various kinds of Mn structures as well as several theoretical methods with their own limitations to handle the corresponding problems. More precisely, section 2 outlines a variety of bulk, surface, interface and cluster structures with their resulting magnetism as far as Mn is concerned. Actually, in these past two decades, considerable interest has been devoted to Mn nanostructures deposited on various metallic substrates (section 3). Because of its exotic structural and magnetic properties, Mn is indeed an interesting candidate for ultra-thin film growth as it is expected to accept different local configurations. Experimentally, one may attempt to stabilize normally high-temperature phases of Mn by epitaxial growth on a suitable substrate. Specifically, we shall point out the frequently occurring, important situation of magnetically stabilized surface alloys. Next (section 4) we first focus on spectroscopic properties of Mn compounds as well as Mn adsorbates upon graphite and other substrates both experimentally and theoretically. Moreover, we recall a few remarks about Mn impurities with respect to the Kondo problem and also with respect to semiconductors and spintronics. In the latter field, practical applications actually require room-temperature Mn ferromagnetism which is not that easy to obtain. Finally, in section 5, we point out that a given Mn nanostructure generally exhibits a non-collinear (NCL) structure which is often the most stable one among all the collinear and NCL ones. This fact explains why constrained collinear calculations have often disagreed with the corresponding experimental data. Section 6 is devoted to a short discussion where we recall a few important points that have been developed in this paper.

59 citations