A5049630348- Crystallography and Radiation Phenomena
- Advanced X-ray Imaging Techniques
- Magnetism in coordination complexes
- X-ray Diffraction in Crystallography
- X-ray Spectroscopy and Fluorescence Analysis
- Magnetic properties of thin films
- High-pressure geophysics and materials
- Electron Spin Resonance Studies
- Lanthanide and Transition Metal Complexes
- Magnetic Properties and Applications
- Microstructure and mechanical properties
- Nuclear materials and radiation effects
- Advanced NMR Techniques and Applications
- Rare-earth and actinide compounds
- Advanced Electron Microscopy Techniques and Applications
- Magnetic Properties of Alloys
- Topological Materials and Phenomena
- Advanced Condensed Matter Physics
- Particle Accelerators and Free-Electron Lasers
- Semiconductor materials and interfaces
- Crystallization and Solubility Studies
- Metal-Catalyzed Oxygenation Mechanisms
- Enzyme Structure and Function
- Atomic and Molecular Physics
- Ion-surface interactions and analysis
Deutsches Elektronen-Synchrotron DESY
2014-2023
UGC DAE Consortium for Scientific Research
2020
European Synchrotron Radiation Facility
2004-2017
University of Johannesburg
2017
Oak Ridge National Laboratory
2017
A.V. Shubnikov Institute of Crystallography
2017
Lomonosov Moscow State University
2017
Photonics Electronics Technology Research Association
2013
Universität Hamburg
2000-2003
Osaka University
1995
Abstract Crystallization of an amorphous solid is usually accompanied by a significant change transport properties, such as increase in thermal and electrical conductivity. This fact underlines the importance crystalline order for charge heat. Phase‐change materials, however, reveal remarkably low conductivity state. The small this upon crystallization points to unique lattice properties. present investigation reveals that properties state phase‐change materials show remarkable differences...
The lattice dynamics in Bi${}_{2}$Te${}_{3}$ and Sb${}_{2}$Te${}_{3}$ were investigated both microscopically macroscopically using ${}^{121}$Sb ${}^{125}$Te nuclear inelastic scattering, x-ray diffraction, heat capacity measurements. In combination with earlier neutron scattering data, the element-specific density of phonon states was obtained for compounds polarization analysis carried out Bi${}_{2}$Te${}_{3}$. A prominent peak Te specific at $13\phantom{\rule{0.28em}{0ex}}\mathrm{meV}$,...
The control of light-matter interaction at the quantum level usually requires coherent laser fields. But already an exchange virtual photons with electromagnetic vacuum field alone can lead to coherences, which subsequently suppress spontaneous emission. We demonstrate such spontaneously generated coherences (SGC) in a large ensemble nuclei operating x-ray regime, resonantly coupled common cavity environment. observed SGC originates from two fundamentally different mechanisms related...
Resonant oscillators with stable frequencies and large quality factors help us to keep track of time high precision. Examples range from quartz crystal in wristwatches atomic clocks, which are, at present, our most precise measurement devices1. The search for more convenient reference is continuing2-6. Nuclear are better than because their naturally higher resilience against external perturbations7-9. One the promising cases an ultra-narrow nuclear resonance transition 45Sc between ground...
Photoabsorption by and fluorescence of the $K\ensuremath{\alpha}$ transitions in highly charged iron ions are essential mechanisms for x-ray radiation transfer astrophysical environments. We study photoabsorption due to main from heliumlike fluorinelike (${\mathrm{Fe}}^{24+}$ ${\mathrm{Fe}}^{17+}$) using monochromatic x rays around 6.6 keV at PETRA III synchrotron photon source. Natural linewidths were determined with hitherto unattained accuracy. The observed particular interest...
Modern x-ray light sources promise access to structure and dynamics of matter in largely unexplored spectral regions. However, the desired information is encoded intensity phase, whereas detectors register only intensity. This phase problem ubiquitous crystallography imaging impedes exploration quantum effects at energies. Here, we demonstrate phase-sensitive measurements characterizing state a nuclear two-level system hard The nuclei are initially prepared superposition state. Subsequently,...
Group velocity control is demonstrated for x-ray photons of 14.4 keV energy via a direct measurement the temporal delay imposed on spectrally narrow pulses. Subluminal light propagation achieved by inducing steep positive linear dispersion in optical response Fe57 Mössbauer nuclei embedded thin film planar cavity. The detection pulse enabled generating frequency-tunable pulses from broadband pulsed synchrotron radiation. Our theoretical model good agreement with experimental data.Received 29...
A heterotrinuclear [Pt2Fe] spin crossover (SCO) complex was developed and synthesized employing a ditopic bridging bpp-alkynyl ligand L alkynyl coordinated PtII terpy units: [FeII(L-PtII)2]2(BF4)2 (1). We identified two different types of crystals 1 which differ in their molecular packing the number co-crystallized solvent molecules: 1H (1·3.5CH2Cl2 P1[combining macron]) 1L (1·10CH2Cl2 C2/c); while shows reversible SCO with transition temperature 268 K, analogous compound does not show any...
Spectroscopy of nuclear resonances offers a wide range applications due to the remarkable energy resolution afforded by their narrow linewidths. However, progress toward higher is inhibited at modern x-ray sources because they deliver only tiny fraction photons on resonance, with remainder contributing an off-resonant background. We devised experimental setup that uses fast mechanical motion resonant target manipulate spectrum given pulse and redistribute spectral intensity onto resonance....
Coherent control of quantum dynamics is key to a multitude fundamental studies and applications
The lattice parameters of α-Al 2 O 3 have been measured in a temperature range from 4.5 to 250 K with relative accuracy better than 6 × 10 −6 . experimental method uses Bragg backscattering and the recently proposed Mössbauer wavelength standard, i.e. λ M = 86.025474 (16) pm nuclear resonance radiation 57 Fe (Shvyd'ko et al. , 2000), which has previously applied successfully measure at temperatures between 286 374 2002). data are consistent Debye model thermal expansion. At K, expansion...
A sapphire backscattering monochromator with 1.1 (1) meV bandwidth for hard X-rays (20-40 keV) is reported. The optical quality of several crystals has been studied and the best crystal was chosen to work as monochromator. small energy obtained by decreasing volume impinged upon beam choosing part quality. tested at energies nuclear resonances (121)Sb 37.13 keV, (125)Te 35.49 (119)Sn 23.88 (149)Sm 22.50 keV (151)Eu 21.54 keV. For each energy, specific reflections temperatures in 150-300 K...
The beamline P01, actually under construction at the PETRA III synchrotron in Hamburg, will be dedicated to nuclear resonant scattering (NRS) and inelastic x-ray (IXS). It profit from a 20m long straight section with four 5m undulator-segments. Due resulting outstanding brilliance combination micron sub-micron focussing of beam P01 especially well suited study small samples nano- extreme condition science. In this paper is introduced future possibilities applying spectroscopy are discussed.
Identification of unstable high-valent iron species in decomposition ferrate(<sc>vi</sc>) advances the understanding mechanisms by ferrates.
We have measured, by x-ray backscattering, the lattice constant of four highly enriched Ge isotopes: $A=70,$ 73, 74, and 76 at temperatures ranging from 8 to 300 K. Comparing with ${}^{70}\mathrm{Ge},$ values $\ensuremath{\Delta}a/a$ ranged $\ensuremath{-}10$ $\ensuremath{-}46$ p.p.m. A good quantitative agreement over whole temperature range (8--300 K) was found calculated a theory that takes into account zero point motion anharmonicity lattice.
We demonstrate an interferometer for hard x rays with two back-reflecting sapphire crystal mirrors--a prototype x-ray Fabry-Pérot interferometer. A finesse of 15 and 0.76 mu eV broad transmission resonances are measured by the time response Interference patterns observed directly in spectral dependences reflectivity.
The wavelength of the 57Fe Mössbauer radiation is measured with a relative uncertainty 0.19 ppm by using almost exact Bragg backscattering from reference silicon crystal. Its value determined as lambda(M) = 0.860 254 74(16)x10(-10) m. corresponding photon energy E(M) 14 412.497(3) eV. easily reproducible an accuracy at least 10(-11)lambda(M) and could be used length standard atomic dimensions.
The ultrahigh resolution IXS beamline of NSLS-II is designed to probe a region dynamic response that requires an energy and momentum up 0.1 meV < nm−1 respectively, which currently still beyond the reach existing low high frequency inelastic scattering probes. Recent advances at in developing required x-ray optics instrumentation based on use extremely asymmetric Bragg back reflections Si have allowed us achieve sub-meV with sharp tails efficiency medium around 9.1 keV, thereby validating...
The density of phonon states in the thermoelectric material Yb${}_{14}$MnSb${}_{11}$ has been studied first by inelastic neutron scattering and second an element-specific way nuclear x-ray scattering. low sound velocity 1880(50) m/s as obtained from can be identified important reason for heat transport this system. high melting temperature contrasts with energy all phonons ($<$25 meV) relates to unusual lack softening modes temperature, when comparing observed at ambient temperatures 1200 K....
An unparalleled resolution is reported with an inelastic x-ray scattering instrument at the Cu K-edge. Based on a segmented concave analyzer, featuring single crystal quartz (SiO_{2}) pixels, spectrometer delivers near 25 meV (FWHM) 8981 eV. Besides performance of relies four-bounce Si(553) high-resolution monochromator and focusing Kirkpatrick-Baez optics. The measured agrees ray tracing simulation ideal spectrometer. We demonstrated by reproducing phonon dispersion curve beryllium (Be) crystal.
We study two fundamental transitions from the ground state $^{1}S_{0}$ to $^{1}P_{1}$ ($w$ line) and $^{3}P_{1}$ ($y$ in heliumlike ${\mathrm{Kr}}^{34+}$ by resonant single-photon excitation using an electron-beam ion trap monochromatic x rays at PETRA III. Our results for transition energies $E(w)=13\phantom{\rule{0.16em}{0ex}}114.47(14)$ eV $E(y)=13\phantom{\rule{0.16em}{0ex}}026.15(14)$ are excellent agreement with quantum electrodynamics calculations, but disagree $w$ average of hitherto...