scholarly journals Новые линии в спектрах ИК люминесценции высокого разрешения монокристаллов SiC политипов 4H и 6H

2020 ◽  
Vol 128 (9) ◽  
pp. 1264
Author(s):  
К.Н. Болдырев ◽  
Д.Д. Гуценко ◽  
С.А. Климин ◽  
Н.Н. Новикова ◽  
Б.Н. Маврин ◽  
...  
Keyword(s):  
High Resolution ◽  
Low Temperature ◽  
Single Crystals ◽  
Absorption Spectra ◽  
High Energy ◽  
High Quality ◽  
High Energy Part ◽  
Infrared Luminescence ◽  
Energy Part ◽  
First Time

Low-temperature infrared luminescence and high-resolution absorption spectra of undoped high-quality SiC single crystals of hexagonal modifications 4H and 6H were investigated. Narrow lines with widths less than 0.2 cm^(-1) were detected, several of which were observed for the first time. It was found that some of the lines in the 4H and 6H modifications have a similar structure, however, the lines in SiC-4H are shifted to the high-energy part of the spectrum by ~ 180 cm^(-1). For the most intense quartet in the region of 1.3 μm, the energy scheme of the levels for both 4H and 6H modifications were constructed.

scholarly journals High-quality quartz single crystals for high-energy-resolution inelastic X-ray scattering analyzers

2013 ◽  
Vol 46 (4) ◽  
pp. 939-944 ◽  
Author(s):  
Marcelo Goncalves Hönnicke ◽  
Xianrong Huang ◽  
Cesar Cusatis ◽  
Chaminda Nalaka Koditwuakku ◽  
Yong Q. Cai
Keyword(s):  
High Resolution ◽  
Single Crystals ◽  
Energy Resolution ◽  
High Energy ◽  
High Energy Resolution ◽  
High Quality ◽  
X Ray ◽  
X Ray Scattering ◽  
Low Energies ◽  
Ray Scattering

Spherical analyzers are well known instruments for inelastic X-ray scattering (IXS) experiments. High-resolution IXS experiments almost always use Si single crystals as monochromators and spherical analyzers. At higher energies (>20 keV) Si shows a high energy resolution (<10 meV), at an exact symmetric back-diffraction condition, since the energy resolution is given by the real part of the susceptibility or polarizability. However, at low energies (<10 keV), high energy resolution is difficult to achieve with Si. α-SiO2 (quartz) can be an option, since it offers high energy resolution at low energies. In this work, the characterization of high-quality α-SiO2 is presented. Such characterization is made by high-resolution rocking curve, topography and lattice parameter mapping in different samples from a single block. X-ray optics with α-SiO2 for IXS at lower energies (from 2.5 to 12.6 keV) with medium to high energy resolution (from 90 to 11 meV) are proposed and theoretically exploited.

Compact back-scattered electrons' energy analyzer for standard SEM

1994 ◽  
Vol 52 ◽  
pp. 488-489
Author(s):  
S. Likharev ◽  
A. Kramarenko ◽  
V. Vybornov
Keyword(s):  
Depth Resolution ◽  
High Energy ◽  
Primary Beam ◽  
Layer By Layer ◽  
Energy Analyzer ◽  
High Energy Part ◽  
Small Window ◽  
Energy Part ◽  
Wide Range ◽  
High Voltage Supply

At present time the interest is growing considerably for theoretical and experimental analysis of back-scattered electrons (BSE) energy spectra. It was discovered that a special angle and energy nitration of BSE flow could be used for increasing a spatial resolution of BSE mode, sample topography investigations and for layer-by layer visualizing of a depth structure. In the last case it was shown theoretically that in order to obtain suitable depth resolution it is necessary to select a part of BSE flow with the directions of velocities close to inverse to the primary beam and energies within a small window in the high-energy part of the whole spectrum.A wide range of such devices has been developed earlier, but all of them have considerable demerit: they can hardly be used with a standard SEM due to the necessity of sufficient SEM modifications like installation of large accessories in or out SEM chamber, mounting of specialized detector systems, input wires for high voltage supply, screening a primary beam from additional electromagnetic field, etc. In this report we present a new scheme of a compact BSE energy analyzer that is free of imperfections mentioned above.

scholarly journals Multiple retrograde substructures in the Galactic halo: A shattered view of Galactic history

2019 ◽  
Vol 631 ◽  
pp. L9 ◽  
Author(s):  
Helmer H. Koppelman ◽  
Amina Helmi ◽  
Davide Massari ◽  
Adrian M. Price-Whelan ◽  
Tjitske K. Starkenburg
Keyword(s):  
High Resolution ◽  
Clustering Algorithm ◽  
Galactic Halo ◽  
High Energy ◽  
Galaxy Mergers ◽  
Chemical Abundance ◽  
Distinct Structure ◽  
Halo Stars ◽  
Energy Part ◽  
Hydrodynamical Simulations

Aims. Several kinematic and chemical substructures have been recently found amongst Milky Way halo stars with retrograde motions. It is currently unclear how these various structures are related to each other. This Letter aims to shed light on this issue. Methods. We explore the retrograde halo with an augmented version of the Gaia DR2 RVS sample, extended with data from three large spectroscopic surveys, namely RAVE, APOGEE, and LAMOST. In this dataset, we identify several structures using the HDBSCAN clustering algorithm. We discuss their properties and possible links using all the available chemical and dynamical information. Results. In concordance with previous work, we find that stars with [Fe/H] < −1 have more retrograde motions than those with [Fe/H] > −1. The retrograde halo contains a mixture of debris from objects like Gaia-Enceladus, Sequoia, and even the chemically defined thick disc. We find that the Sequoia has a smaller range in orbital energies than previously suggested and is confined to high energy. Sequoia could be a small galaxy in itself, but since it overlaps both in integrals-of-motion space and chemical abundance space with the less bound debris of Gaia-Enceladus, its nature cannot yet be fully settled. In the low-energy part of the halo, we find evidence for at least one more distinct structure: Thamnos. Stars in Thamnos are on low-inclination, mildly eccentric retrograde orbits, moving at vϕ ≈ −150 km s−1, and are chemically distinct from the other structures. Conclusions. Even with the excellent Gaia DR2 data, piecing together all the fragments found in the retrograde halo remains challenging. At this point, we are very much in need of large datasets with high-quality high-resolution spectra and tailored high-resolution hydrodynamical simulations of galaxy mergers.

The Preparation of C60/C70 and the Characterization by Different Techniques

1992 ◽  
Vol 270 ◽  
Author(s):  
P. Häussler ◽  
H. Bestgen ◽  
H.-U. ter Meer
Keyword(s):  
Electron Microscopy ◽  
Mass Spectrometry ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Single Crystals ◽  
Absorption Spectra ◽  
Preparation Conditions ◽  
Transmission Electron ◽  
Method Evidence ◽  
Fcc Structure

ABSTRACTWe report on the preparation of C60/C70 by the arc method. Evidence of monofunctional C60O, and C60-CH2 has been observed by mass spectrometry. Dependent on their preparation conditions, high resolution transmission electron microscopy of crystals consisting of mixtures of C60/C70 show different structure. Needle-like crystals grown from toluene show superlattice formation while single crystals obtained by sublimation have fcc structure. UV-VIS-absorption spectra in toluene are compared to those of films of various thickness and crystallinity.

STUDY OF COMPLEX Cu-O LATTICE IN La8-xSrxCu8O20 BY HIGH RESOLUTION X-RAY ABSORPTION SPECTROSCOPY

2000 ◽  
Vol 14 (29n31) ◽  
pp. 3656-3661 ◽  
Author(s):  
N. L. SAINI ◽  
A. LANZARA ◽  
K. B. GARG ◽  
A. BIANCONI ◽  
T. ITO ◽  
...  
Keyword(s):  
High Resolution ◽  
Single Crystals ◽  
Absorption Spectroscopy ◽  
Local Structure ◽  
Three Dimensional ◽  
Xanes Spectroscopy ◽  
High Quality ◽  
X Ray ◽  
X Ray Absorption

Cu K-edge XANES spectroscopy has been used to study local structure around the Cu-site in three-dimensional oxygen deficient perovkite La 8- x Sr x Cu 8 O 20 system. The combination of E//ab and E//c polarization and high resolution XANES spectra on high quality single crystals has allowed us to distinguish the various features associated with the complex Cu-O networks in the system which have then been compared with those of the La 2- x Sr x CuO 4 system.

HIGH-RESOLUTION HYPERNUCLEAR SPECTROSCOPY ELECTRON SCATTERING AT JLab, HALL A

2010 ◽  
Vol 19 (12) ◽  
pp. 2487-2496 ◽  
Author(s):  
◽  
F. Garibaldi ◽  
E. Cisbani ◽  
F. Cusanno ◽  
S. Frullani ◽  
...  
Keyword(s):  
Electron Beam ◽  
High Resolution ◽  
Energy Resolution ◽  
Electron Scattering ◽  
Ground State ◽  
Missing Energy ◽  
High Quality ◽  
The Core ◽  
Final Data ◽  
First Time

The characteristics of the Jefferson LAB electron beam, together with those of the experimental equipments, offer a unique opportunity to study hypernuclear spectroscopy via electromagnetic induced reactions. Experiment 94-107 started a systematic study on 1p-shell targets, 12 C , 9 Be and 16 O . We present the results from 12 C , 16 O and very preliminary results from 9 Be . For 12 C for the first time measurable strength in the core-excited part of the spectrum between the ground state and the pΛ state was shown in [Formula: see text] for the first time. A high-quality 16Λ N spectrum was produced for the first time with sub-MeV Energy resolution. A very precise B Λ value for 16Λ N , calibrated against the elementary ( e , e ′ K +) reaction on hydrogen, has also been obtained. Final data on 9 Be will be available soon. The missing energy resolution is the best ever obtained in hypernuclear production experiments.

High-Resolution X-Ray Microstructural Study of Single Crystals of YBa2Cu3O7-y

1987 ◽  
Vol 99 ◽  
Author(s):  
Hoydoo You ◽  
J. D. Axe ◽  
X. B. Kan ◽  
S. C. Moss ◽  
J. Z. Liu ◽  
...  
Keyword(s):  
High Resolution ◽  
Diffraction Study ◽  
Single Crystals ◽  
Growth Conditions ◽  
High Energy ◽  
Synchrotron Source ◽  
Microstructural Study ◽  
X Ray ◽  
Oxygen Ordering ◽  
New Type

ABSTRACTSingle crystals of YBa2Cu3O7-y were studied by transmission Laue photography and monochromatic diffraction techniques, using the Cornell High Energy Synchrotron Source and a rotating anode x-ray source. A new type of twinning, with two orthorhombic domains rotated exactly 90 degree about the c axis, was observed in one sample and the conventional (110) type twinning in another sample with nominally identical growth conditions. A high resolution diffraction study of the sample with the conventional (110) twinning shows that measured orthorhombicity (proportional to oxygen ordering parameter) varies from one domain to another.

Sign in / Sign up

Export Citation Format

Share Document