Temperature-dependent forbidden resonant x-ray scattering in zinc oxide

Collins, Stephen P.; Laundy, D.; Дмитриенко, В. Е.; Mannix, D.; Thompson, Patrick L.

doi:10.1103/physrevb.68.064110

Cited by 37 publications

(62 citation statements)

References 13 publications

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“…It can, however, also be observed at higher energies in the EXAFS region where its structural interpretation is more obvious (García et al, 2000;Collins et al, 2003;.…”

Section: Acta Cryst (2005) A61 481-493mentioning

confidence: 99%

“…These observations can be rationalized in terms of an interference of the dd TMI effect with an electronic dq transition which has very different energy profiles. Collins et al (2003) were able to model the complicated pattern of Ið115; E; TÞ by a function which describes the effects of a complex solely energy dependent transition structure factor and a term that is both energy and temperature dependent for isotropic atomic displacements corresponding to a low-lying phonon branch with characteristic frequency ! 0 .…”

Section: Thermal-motion-induced and Defect-induced Reflectionsmentioning

confidence: 99%

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Polarization anisotropy of X-ray atomic factors and `forbidden' resonant reflections

et al. 2005

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Symmetry and physical aspects of 'forbidden' reflections excited by a local polarization anisotropy of the X-ray susceptibility are surveyed. Such reflections are observed near absorption edges where the anisotropy is caused by distortions of the atomic electronic states owing to interaction with neighbouring atoms. As a consequence, they allow for extracting nontrivial information about the resonant atom's local environment and their physical conditions. The unusual polarization properties of the considered reflections are helpful to distinguish them from other types of 'forbidden' reflections. When such reflections are excited, it is, for example, possible to determine not only the intrinsic anisotropy of an atomic form factor but also additional anisotropy induced by thermal motion, point defects and/or incommensurate modulations. Even the local 'chirality' of atoms in centrosymmetric crystals is accessible. Unsolved key problems and possible future developments are addressed.

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“…It can, however, also be observed at higher energies in the EXAFS region where its structural interpretation is more obvious (García et al, 2000;Collins et al, 2003;.…”

Section: Acta Cryst (2005) A61 481-493mentioning

confidence: 99%

Section: Thermal-motion-induced and Defect-induced Reflectionsmentioning

confidence: 99%

Polarization anisotropy of X-ray atomic factors and `forbidden' resonant reflections

et al. 2005

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“…, and cannot account for the temperature dependence of forbidden reflections in Ge, ZnO and GaN, in which the E1E1 term also vanishes [28][29][30][31] : in these systems, the intensity of forbidden reflections increases with temperature, despite the Debye-Waller effect, and the intensity growth is accompanied by a change of spectrum that can only be explained by interference with a second scattering process 30,31 . The latter was ascribed to thermal-motion induced (TMI) scattering 32 .…”

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confidence: 99%

Proton configurations in the hydrogen bonds ofKH2PO4as seen by resonant x-ray diffraction

et al. 2015

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KH2PO4 (KDP) belongs to the class of hydrogen-bonded ferroelectrics, whose paraelectric to ferroelectric phase transition is driven by the ordering of the protons in the hydrogen bonds. We demonstrate that forbidden reflections of KDP, when measured at an x-ray absorption edge, are highly sensitive to the asymmetry of proton configurations. The change of average symmetry caused by the 'freezing' of the protons during the phase transition is clearly evidenced. In the paraelectric phase, we identify in the resonant spectra of the forbidden reflections a contribution related to the transient proton configurations in the hydrogen bonds, which violates the high average symmetry of the sites of the resonant atoms. The analysis of the temperature dependence reveals a change of relative probabilities of the different proton configurations. They follow the Arrhenius law and the activation energies of polar and Slater configurations are 18.6 and 7.3 meV respectively.

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“…Furthermore information of the thermal motion correlation was derived from the TMI scattering in germanium [49]. The TMI scattering at a forbidden reflection has been also observed in other crystals, ZnO [50] and GaN [51]. Theoretical simulations show that the TMI scattering is mainly caused by the optical phonon mode [52].…”

Section: Resultsmentioning

confidence: 99%

Anisotropic resonant X-ray scattering: Beauty of forbidden reflections

Kokubun

Дмитриенко

2012

Eur. Phys. J. Spec. Top.

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Abstract. Experimental results and their theoretical explanation are reviewed for fundamentals of anisotropic resonant X-ray scattering. Resonant scattering depends on X-ray polarization, i.e. the scattering reflects anisotropic environment of atoms in crystal. The polarization anisotropy in atomic scattering can excite the forbidden Bragg reflections. Studying this type of forbidden reflections we can distinguish electronic orbitals of specific symmetry. This method is very useful for studying local electronic states in crystal. We reveal detailed property of the anisotropic scattering, effect of quadrupole transition, thermal motion, magnetic scattering and so on. Especially successful examples are given in detail: observation of phase of the scattering factor, the hybridization of states with different parity, local chirality of atom in centrosymmetric crystals, thermal-motion-induced resonant reflections, etc.

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Temperature-dependent forbidden resonant x-ray scattering in zinc oxide

Cited by 37 publications

References 13 publications

Polarization anisotropy of X-ray atomic factors and `forbidden' resonant reflections

Polarization anisotropy of X-ray atomic factors and `forbidden' resonant reflections

Proton configurations in the hydrogen bonds ofKH2PO4as seen by resonant x-ray diffraction

Anisotropic resonant X-ray scattering: Beauty of forbidden reflections

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