X-ray Raman scattering in colloidal and polycrystalline graphite

1980 ◽  
Vol 58 (10) ◽  
pp. 1507-1509 ◽  
Author(s):  
C. N. Koumelis ◽  
C. A. Londos
Keyword(s):  
Raman Scattering ◽  
Short Range ◽  
Raman Band ◽  
Energy Shift ◽  
Crystal Spectrometer ◽  
X Ray ◽  
Polycrystalline Graphite ◽  
Low Energies ◽  
The Difference ◽  
Additional Anomaly

Raman scattering was measured in colloidal and polycrystalline graphite for a scattering angle 45°, using X-ray CrKβ radiation and a mosaic graphite analysing crystal spectrometer without collimators. The use of such a spectrometer was necessary because of the weakness of the Raman effect.For the colloidal graphite, an energy shift of ΔE = 288.3 ± 0.6 eV from the primary line was observed. For the polycrystalline graphite, the above shift was ΔE = 284.9 ± 0.5 eV. These shifts can be ascribed to the transition of the 1s electrons onto and above the Fermi level, constituting the so-called Raman band.In the polycrystalline graphite, an additional anomaly was observed in the spectrum, beyond the Raman band towards the low energies, i.e., in 311 eV. This fine structure is a verification of the Weaire–Thorp concept about the difference in the spectra, due to the short-range and long-range order.

HIGH RESOLUTION L X-RAY EMISSION SPECTRA OF Fe AND Cu INDUCED BY O.75 MeV/u ION IMPACT

1995 ◽  
Vol 05 (02n03) ◽  
pp. 203-209 ◽  
Author(s):  
H. KAGEYAMA ◽  
R. TAKAHASHI ◽  
D. HAMAGUCHI ◽  
T. AWATA ◽  
T. NAKAE ◽  
...  
Keyword(s):  
High Resolution ◽  
Lower Energy ◽  
Emission Spectra ◽  
Crystal Spectrometer ◽  
Transition Energies ◽  
X Ray ◽  
The Difference ◽  
Ion Impact ◽  
Electron Vacancy ◽  
Good Agreement

High resolution L x-ray emission spectra of Fe and Cu have been measured by 0.75 MeV/u H and He, and 0.73 MeV/u He, Si and Ar ion impacts with a crystal spectrometer. The x-ray transition energies in the Fe and Cu targets for Lι, Lη, Lα1,2, Lβ1 and Lβ3,4 diagram lines induced by light ion impacts are determined, which are in good agreement with those given in the reference. The difference in L x-ray emission spectra produced by H, He, Si and Ar ions is considered and the emission spectra for the Cu target are compared with the calculated ones based on the multiconfiguration Dirac-Fock method. The origin of the broadening of the Lα1,2 line to the lower energy for Si and Ar ion impacts is attributed to one 2p plus one 3d electron vacancy production.

Evidence for cooling-rate-dependent icosahedral short-range order in a Cu–Zr–Al metallic glass

2014 ◽  
Vol 47 (6) ◽  
pp. 1906-1911 ◽  
Author(s):  
Helmut Hermann ◽  
Uta Kühn ◽  
Horst Wendrock ◽  
Valentin Kokotin ◽  
Björn Schwarz
Keyword(s):  
Metallic Glass ◽  
Cooling Rate ◽  
Short Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rate Dependent ◽  
Icosahedral Clusters ◽  
Thermal Displacements ◽  
The Difference ◽  
Diffraction Patterns

Samples of Cu47.5Zr47.5Al5metallic glass were prepared at different cooling rate,R. The dependence of the X-ray diffraction patterns onRwas analysed by comparing them with corresponding patterns of computer-simulated models generated at different cooling rates as well. The observed changes in the experimental diffraction patterns are reproduced by the simulations, showing an increasing fraction of icosahedral clusters with decreasing cooling rate. The difference of the fractions of icosahedrally coordinated atoms in mould-cast and rapidly quenched Cu47.5Zr47.5Al5averages to 3 (1)%. Different frozen-in thermal displacements and different density are ruled out as a possible origin for the experimental observations.

X-ray Raman scattering on polycrystalline graphite in the scattering angle range 0–120°

1983 ◽  
Vol 61 (4) ◽  
pp. 629-632 ◽  
Author(s):  
Z. I. Kavogli ◽  
D. K. Leventouri ◽  
C. N. Koumelis
Keyword(s):  
Raman Spectrum ◽  
Raman Scattering ◽  
Raman Line ◽  
Scattering Angle ◽  
X Ray ◽  
Peak Intensity ◽  
Polycrystalline Graphite

X-ray Raman scattering was studied on polycrystalline graphite for various scattering angles in the range 0–120°. A mosaic graphite spectrometer without collimators and Crkβ radiation were used.The shape of the Raman spectrum depended slightly on the scattering angle. The peak intensity of the Raman line increases with scattering angle but in a different way to that resulting from the calculation of Mizuno and Ohmura. Additional components were observed in the spectrum on both sides of the Raman line.

Short-Range Order in KPO3 Glass Studied by Neutron and X-Ray Diffraction

1996 ◽  
Vol 51 (3) ◽  
pp. 179-186 ◽  
Author(s):  
Uwe Hoppe ◽  
Günter Walter ◽  
Dörte Stachel ◽  
Alex C. Hannon
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Lengths ◽  
Spherical Cavities ◽  
The Difference

The short-range order of KPO3 glass has been studied by diffraction methods in order to make evident the different behaviour of the P-O bonds within the PO4 tetrahedron. The oxygen sites are devided into bridging and terminal (non-bridging) oxygen sites, corresponding to two P-O bond lengths, the difference of which amounts to 14.5 pm. Previous conclusions about the changes of the P-O bond lengths under the influence of modifier cations of different electric field strength are corroborated. The K-O environments reveal two apparently different distances rKO with equal contributions to the total K-O coordination number of about 6.7. To explain this phenomenon, the K+ cations are suggested to be located in non-spherical cavities

Mn K-Edge X-Ray Absorption Spectroscopy (XAS) Studies of La1-xSrxMnO3

1997 ◽  
Vol 494 ◽  
Author(s):  
S. M. Mini ◽  
J. F. Mitchells ◽  
D. G. Hinks ◽  
Ahmet Alatasi ◽  
D. Rosenmann ◽  
...  
Keyword(s):  
Manganese Oxide ◽  
Absorption Spectroscopy ◽  
Energy Shift ◽  
Hole Doping ◽  
Oxide Systems ◽  
X Ray ◽  
Colossal Magnetoresistive ◽  
The Difference ◽  
X Ray Absorption ◽  
Made In

ABSTRACTSystematic Mn K-edge x-ray absorption spectroscopy (XAS) measurements on samples of La1-xSrxMnO3, which are precursors to colossal magnetoresistive (CMR) materials, are reported. Detailed results on the edge or chemical shift as a function of Sr concentration (hole doping) and sample preparation (air vs oxygen annealed), are discussed. For comparison, a systematic XANES study of the Mn K-edge energy shift, denoting valence change in Mn, has been made in standard manganese oxide systems. Contrary to expectations, the variation in near-edge energies for Mn in La0.725Sr0.275MnO3 were small when compared to the difference between that for manganese oxide standards of nominal valence of +3 and +4 (Mn2O3 and MnO2).

Structure and Dynamic Properties of Molten Lanthanum Tribromide

1999 ◽  
Vol 54 (2) ◽  
pp. 91-94
Author(s):  
Yoshihiro Okamoto ◽  
Toru Ogawa
Keyword(s):  
Molecular Dynamics ◽  
Shear Viscosity ◽  
Short Range ◽  
Md Simulation ◽  
Dynamic Properties ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Difference ◽  
Short Range Structure

Abstract The structure of molten LaBr3 was investigated by X-ray diffraction and molecular dynamics simu-lations. It was found that the short range structure of molten LaBr3 is very similar to that of molten LaCl 3 , except for some structural features such as interionic distances based on the difference of anion sizes. In the MD simulation, the shear viscosity of molten LaBr3 was estimated from the structurally-optimized MD calculations.

X-Ray Raman scattering in amorphous boron

1978 ◽  
Vol 56 (4) ◽  
pp. 438-439 ◽  
Author(s):  
D. K. Leventouri ◽  
S. S. Vaiopoulos ◽  
A. B. Vassilikou ◽  
C. N. Koumelis
Keyword(s):  
Raman Scattering ◽  
Raman Band ◽  
The Other ◽  
Amorphous Boron ◽  
Scattering Angle ◽  
X Ray ◽  
New Type

Raman scattering was measured using X-ray CrKβ radiation in amorphous boron for a scattering angle 45° and with a new type graphite spectrometer without collimators.Two energy shifts from the primary line were observed, one at a distance of 193 eV, which is ascribed to the Raman band, and the other at a distance of 183 eV, which is ascribed to the 1s–2p transition.

Thermal Stability of the Structural and Electronic Properties of Strain Symmetrized Sim Gen Superlattices and Ungraded, Nearly Relaxed Si1−x Gex

1992 ◽  
Vol 281 ◽  
Author(s):  
P. A. Dafesh ◽  
P. M. Adams ◽  
V. Arbet-Engels ◽  
K. L. Wang
Keyword(s):  
Thermal Expansion ◽  
Energy Shift ◽  
Buffer Layers ◽  
X Ray ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Structural And Electronic Properties ◽  
Expansion Coefficients ◽  
The Difference ◽  
Anneal Temperature

ABSTRACTIn this study, photoreflectance (PR) spectroscopy and x-ray rocking curves measurements were used to study the variation in strain configuration, defect propagation, structural properties and direct electronic transition energies in Sim Gen superlattices (SL) and nearly relaxed Si1−x Gex buffer layers grown on < 100 > Si as a function of annealing temperature. The in-plane (a│) and perpendicular (a┴) lattice constants of the alloy buffer layers are found to vary only slightly with anneal temperature, TA, up to a temperature To. For TA To, the in-plane strain changed from roughly zero a│ ≈ a┴ (relaxed) or a┴ > a│ (compressive) to a┴ > a│ (tensile). This change in strain configuration is believed to be caused by the difference in thermal expansion coefficients between the epilayer and the Si substrate. The anneal temperature T0 is also correlated with the disappearance of higher order x-ray harmonics from the SL. This point was also correlated with a large energy shift and broadening of the PR spectra from the SL. The shift in energy of the PR spectra is explained in terms of the interdiffusion of Si and Ge at SL heterointerfaces, and to a lesser degree, the strain induced by the above mentioned difference in thermal expansion coefficients. The PR spectra of the alloy E0 transitions are also observed to shift to higher energy with increasing TA.

Difference Fourier Analysis of Glucose Embedded and Frozen Hydrated Purple Membrane

1982 ◽  
Vol 40 ◽  
pp. 74-75
Author(s):  
Jules S. Jaffe ◽  
Robert M. Glaeser
Keyword(s):  
Purple Membrane ◽  
Data Set ◽  
High Resolution Data ◽  
X Ray ◽  
X Ray Crystallography ◽  
Fourier Techniques ◽  
Versus Protein ◽  
The Difference ◽  
Difference Fourier ◽  
Ideal Method

Although difference Fourier techniques are standard in X-ray crystallography it has only been very recently that electron crystallographers have been able to take advantage of this method. We have combined a high resolution data set for frozen glucose embedded Purple Membrane (PM) with a data set collected from PM prepared in the frozen hydrated state in order to visualize any differences in structure due to the different methods of preparation. The increased contrast between protein-ice versus protein-glucose may prove to be an advantage of the frozen hydrated technique for visualizing those parts of bacteriorhodopsin that are embedded in glucose. In addition, surface groups of the protein may be disordered in glucose and ordered in the frozen state. The sensitivity of the difference Fourier technique to small changes in structure provides an ideal method for testing this hypothesis.

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