Six-reflection meV-monochromator for synchrotron radiation

Toellner, T. S.; Alataş, Ahmet; Said, Ayman

doi:10.1107/s0909049511017535

Cited by 115 publications

(91 citation statements)

References 18 publications

(20 reference statements)

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“…The incident x-ray energy was 23.88 keV, the nuclear resonance energy of 119 Sn. The energy bandpass of incident beam was reduced to 1.2 meV using a high resolution crystal monochromator [44]. The inelastic signal collected is comprised mainly of 23.88 keV nuclear fluorescence signal, delayed in time relative to the prompt pulse by 20-130 nsec.…”

Section: B Nuclear Resonant Inelastic X-ray Scatteringmentioning

confidence: 99%

Phonon anharmonicity and negative thermal expansion in SnSe

et al. 2016

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The anharmonic phonon properties of SnSe in the Pnma phase were investigated with a combination of experiments and first-principles simulations. Using inelastic neutron scattering (INS) and nuclear resonant inelastic X-ray scattering (NRIXS), we have measured the phonon dispersions and density of states (DOS) and their temperature dependence, which revealed a strong, inhomogeneous shift and broadening of the spectrum on warming. First-principles simulations were performed to rationalize these measurements, and to explain the previously reported anisotropic thermal expansion, in particular the negative thermal expansion within the Sn-Se bilayers. Accurate treatment of the phonon free energy, in addition to the electronic ground state energy, is essential to reproduce the negative thermal expansion. From the phonon DOS obtained with INS and additional calorimetry measurements, we quantify the harmonic, dilational, and anharmonic components of the phonon entropy, heat capacity, and free energy. The origin of the anharmonic phonon thermodynamics is linked to the electronic structure.

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Section: B Nuclear Resonant Inelastic X-ray Scatteringmentioning

confidence: 99%

Phonon anharmonicity and negative thermal expansion in SnSe

et al. 2016

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“…This is an unusually large number. Typically, the angular acceptance of high-resolution x-ray monochromators is in a 10 to 20 µrad range, often requiring collimating optics, such that the x rays from the source to be fully accepted by the monochromator [2,[4][5][6][7][8][9]21]. The only exception to this rule are single bounce monochromators [22], which, however, have a disadvantage of long Lorentzian tails in the spectral resolution function.…”

Section: Cdfdw Angular Acceptancementioning

confidence: 99%

“…The intrinsic Bragg bandwidth can be reduced [2][3][4][5][6][7][8][9] by using the so-called asymmetric x-ray diffraction, diffraction from atomic planes at nonzero angle η to the crystal face - Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Using angular dispersion and anomalous transmission to shape ultramonochromatic x rays

et al. 2011

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Optical spectrometers, instruments that work with monochromatic light, are commonly rated by the spectral bandwidth, which defines the ability to resolve closely spaced spectral components. The ability to detect faint objects among these components, spectral contrast, is another desired aspect.Here we demonstrate that a combined effect of angular dispersion (AD) and anomalous transmission (AT) of x rays in Bragg reflection from asymmetrically cut crystals can shape spectral distributions of x rays to profiles with record high contrast and small bandwidths.The AD&AT x-ray optics is implemented as a five-reflection three-crystal arrangement featuring a combination of the above mentioned attributes, so much desirable for x-ray monochromators and analyzers: a spectral contrast of 500, a bandwidth of 0.46 meV and a remarkably large angular acceptance of 107 µrad. The new optics can become a foundation for the next generation inelastic x-ray scattering spectrometers for studies of atomic dynamics.

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“…The experiments were conducted at beamline 30-ID-C (HERIX [34,35]) at the Advanced Photon Source (APS). The highly monochromatic x-ray beam of incident energy E i ≃ 23.7 keV (λ = 0.5226Å) had an energy resolution ∆E i ∼ 1.0 meV (full width at half maximum), and was focused on the sample with a beam cross-section ∼ 35 × 15 µm (horizontal×vertical).…”

Section: Inelastic X-ray Scatteringmentioning

confidence: 99%

Lattice dynamics and thermal transport in multiferroicCuCrO2

et al. 2017

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Inelastic neutron and x-ray scattering measurements of phonons and spin waves were performed in the delafossite compound CuCrO2 over a wide range of temperature, and complemented with first-principles lattice dynamics simulations. The phonon dispersions and density of states are well reproduced by our density functional calculations, and reveal a strong anisotropy of Cu vibrations, which exhibit low-frequency modes of large amplitude parallel to the basal plane of the layered delafossite structure. The low frequency in-plane modes also show a systematic temperature dependence of neutron and x-ray scattering intensities. In addition, we find that spin fluctuations persist above 300 K, far above the Néel temperature for long-range antiferromagnetic order, T N ≃ 24 K. Our modeling of the thermal conductivity, based on our phonon measurements and simulations, reveals a significant anisotropy and indicates that spin fluctuations above T N constitute an important source of phonon scattering, considerably suppressing the thermal conductivity compared to that of the isostructural but non-magnetic compound CuAlO2.

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Six-reflection meV-monochromator for synchrotron radiation

Cited by 115 publications

References 18 publications

Phonon anharmonicity and negative thermal expansion in SnSe

Phonon anharmonicity and negative thermal expansion in SnSe

Using angular dispersion and anomalous transmission to shape ultramonochromatic x rays

Lattice dynamics and thermal transport in multiferroicCuCrO2

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