Dispersion of Solid State Excitations

1973 ◽  
Vol 31 ◽  
pp. 284-285
Author(s):  
C. H. Chen ◽  
J. Silcox ◽  
R. Vincent
Keyword(s):  
Electron Microscope ◽  
Solid State ◽  
Small Angle ◽  
Angular Resolution ◽  
High Angular Resolution ◽  
Electron Spectrometer ◽  
Angle Scattering ◽  
Light Line ◽  
Angular Scattering ◽  
Small Angle Region

The addition of an electron spectrometer to an electron microscope extends the capabilities not only of the microscope but also of the electron spectrometer. Operation of the electron microscope in the high angular resolution, small angle scattering mode (see, for example, Wade and Silcox) extends the angular scattering range of the electron spectrometer into an interesting small angle region (<10−4 radians) hitherto inaccessible. The dispersion of many solid state excitations in the energy range leV to 20eV is strongly affected by the light line w = ck where the energy loss ΔE = ђw and the momentum transfer is ђk. These effects can be observed directly by the electron microscope/spectrometer combination at scattering angles <10-4 radians.

Small-Angle Electron Scattering (SAES) of Polymers

1985 ◽  
Vol 43 ◽  
pp. 78-79
Author(s):  
Ralph Oralor ◽  
Pamela Lloyd ◽  
Satish Kumar ◽  
W. W. Adams
Keyword(s):  
Electron Scattering ◽  
Small Angle ◽  
Angular Resolution ◽  
Structural Features ◽  
Objective Lens ◽  
High Angular Resolution ◽  
Push Button ◽  
First Case ◽  
Diffraction Mode ◽  
Very High

Small angle electron scattering (SAES) has been used to study structural features of up to several thousand angstroms in polymers, as well as in metals. SAES may be done either in (a) long camera mode by switching off the objective lens current or in (b) selected area diffraction mode. In the first case very high camera lengths (up to 7Ø meters on JEOL 1Ø ØCX) and high angular resolution can be obtained, while in the second case smaller camera lengths (approximately up to 3.6 meters on JEOL 1Ø ØCX) and lower angular resolution is obtainable. We conducted our SAES studies on JEOL 1ØØCX which can be switched to either mode with a push button as a standard feature.

The Use of a Multi-Double-Crystal Diffractometer to Investigate Nickel Domains

1997 ◽  
Vol 30 (5) ◽  
pp. 849-853 ◽  
Author(s):  
W. Treimer ◽  
A. Höfer ◽  
H. Strothmann
Keyword(s):  
Single Crystals ◽  
Domain Structure ◽  
Small Angle ◽  
Angular Resolution ◽  
Main Peak ◽  
High Angular Resolution ◽  
Bloch Wall ◽  
Double Crystal ◽  
First Results ◽  
Double Crystal Diffractometer

The investigations of the domain structure in Ni single crystals is best performed with a double-crystal diffractometer. Conventional small-angle instruments do not have the necessary angular resolution to distinguish satellites of a main peak due to spin-dependent refraction of unpolarized neutrons by Bloch walls in Ni. With the help of a double-crystal diffractometer operating with lamellae crystals as monochromator and analyzer, the angular resolution is maintained but the intensity enhanced by a factor of 5.4. Within a series of measurements, it was possible to investigate Ni domains due to the high angular resolution of the new multi-double-crystal instrument and this improved intensity. The first results of the domain structure in (110) Ni single crystals and a good estimation of the Bloch wall thickness are given.

An X-Ray Small-Angle Scattering Instrument

1967 ◽  
Vol 11 ◽  
pp. 332-338 ◽  
Author(s):  
Donald M. Koffman
Keyword(s):  
Small Angle ◽  
Scintillation Counter ◽  
Small Angle Scattering ◽  
High Angular Resolution ◽  
X Ray Diffraction ◽  
Multiple Diffraction ◽  
Double Crystal ◽  
X Ray ◽  
Angle Scattering ◽  
Diffraction Patterns

AbstractAn X-ray small-angle scattering instrument is described which is used for recording X-ray diffraction patterns or small-angle X-ray scattering curves in an angular region very close to the direct beam. The measurement of X-ray intensity is accomplished with standard geiger or scintillation counter techniques. The instrument is designed for use with a spot-focus or vertical-line X-ray source, In essence, it is a multiple-reflection double-crystal diffractometer, based on a concept developed by Bonse and Hart, employing two grooved perfect germanium crystals arranged in the parallel position. Multiple diffraction from these crystals produces a monochromated X-ray beam which can be several millimeters wide while still exhibiting extremely high angular resolution. As a result, effective sample volumes can be employed with maximum volume-to-thickness ratios. The principal features of the instrument are discussed with emphasis on the advantages of this device over those employing complex slit systems and film-re cording techniques, Data are presented to illustrate the operation, intensity, and resolution of the unit.

scholarly journals Application of small-angle scattering to study the effects of moisture content on a native soy protein

2008 ◽  
Vol 41 (3) ◽  
pp. 628-633 ◽  
Author(s):  
Catherine S. Kealley ◽  
Margaret M. Elcombe ◽  
Richard Wuhrer ◽  
Elliot P. Gilbert
Keyword(s):  
Moisture Content ◽  
Small Angle ◽  
Soybean Protein ◽  
Surrounding Medium ◽  
Minimal Change ◽  
X Rays ◽  
Moisture Contents ◽  
Angle Scattering ◽  
20 Nm ◽  
Small Angle Region

The nano- and microstructure of glycinin, a soybean protein, has been investigated as a function of moisture for moisture contents between 4 and 21 wt%. Glycinin exhibits peaks in the small-angle region whose positions show minimal change with X-rays for samples up to 13% moisture. However, the use of neutron scattering, and the associated enhancement in contrast, results in the Bragg peaks being well resolved up to higher moisture contents; the associated shift in peak positions between 4 and 21% moisture are consistent with the expansion of a hexagonal unit cell as a function of moisture content. A Porod slope of ∼−4 indicates that the interface between the `dry' protein powder and the surrounding medium at a length-scale of at least 3 µm down to ∼20 nm is smooth and sharp. Scanning electron microscopy indicates that the powders, with low moisture content, have a porous appearance, with the porosity decreasing and microstructure expanding as the moisture content increases.

scholarly journals High-Angular-Resolution Camera Coupled with an Undulator Source at the European Synchrotron Radiation Facility High-Brilliance Beamline

1997 ◽  
Vol 30 (5) ◽  
pp. 862-866 ◽  
Author(s):  
O. Diat ◽  
P. Bösecke ◽  
L. Lambard ◽  
P. P. E. A. de Moor
Keyword(s):  
Synchrotron Radiation ◽  
Small Angle ◽  
Angular Resolution ◽  
European Synchrotron Radiation Facility ◽  
High Angular Resolution ◽  
X Ray

The performance of a high-angular-resolution small-angle X-ray camera combined with an undulator source is presented in the form of examples.

Angle-energy analyzers of back-scattered electrons for layer-by-layer diagnostics of microelectronics devices in Scanning Electron Microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1692-1693
Author(s):  
S.K. Likharev
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Small Angle ◽  
Large Angle ◽  
High Energy ◽  
Small Angle Scattering ◽  
Layer By Layer ◽  
Angle Scattering ◽  
Large Angle Scattering ◽  
Scanning Electron

In previous work it was shown that it was possible to visualize depth microstructure of solidstate samples in layer-by-layer form using some modifications of the back-scattered electron (BSE) detector system in the scanning electron microscope. The approach is based on the idea to detect not all of the BSE current, but only the part of it 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. The fact is that when primary electrons scatter in sample, consisting only of light elements, the process of their elastic scattering can be formally divided on two-parts: small-angle scattering and large-angle scattering. In this case the probability of small-angle scattering is approximately five orders higher than large-angle scattering. Taking into account that energy of an electron can be considered as decreasing continuously, if an electron scatters in a sample and comes out with the velocity mentioned above, one can say, that it most probably passed exactly one large-angle scattering in a sample media.

High Angular Resolution Measurements Of K Shell X-Ray Emission Created by Electron Channeling in the Analytical Electron Microscope

1999 ◽  
Vol 5 (S2) ◽  
pp. 712-713
Author(s):  
Nestor J. Zaluzec
Keyword(s):  
Electron Microscope ◽  
Angular Resolution ◽  
Theoretical Calculations ◽  
High Angular Resolution ◽  
Two Dimensional ◽  
Site Specific ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Impurity Elements

Since the original observations by Duncumb in 1962, a number of studies have been conducted on the effects of electron channel on characteristic x-ray emission and microanalysis. Most of the recent studies have concentrated upon using the phenomenon to perform site specific distributions of impurity elements in ordered compounds using the ALCHEMI methodology. Very few studies have attempted to accurately measure the effect as a function of orientation and compare these results to theory. In this study, two dimensional high angular resolution studies of channeling enhance x-ray emission were performed and herein the results are compared to theoretical calculations of Allen etal.All experimental measurements presented here were conducted on a Philips EM 420T analytical electron microscope. The instrument was operated in the TEM mode, at 120 kV using an LaB6 electron source. The characteristic x-ray emission was measured using an EDAX ultra thin window Si(Li) detector having a FWHM of ∼ 145 eV at Mn Kα.

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