Negative Ion Resonance Evidenced by Vibrationally Resolved Electron Diffraction On the H/Si(111) Surface

1998 ◽  
Vol 05 (01) ◽  
pp. 63-67
Author(s):  
Y. He ◽  
L.-M. Yu ◽  
P. A. Thiry ◽  
R. Caudano
Keyword(s):  
Electron Diffraction ◽  
Resonant Scattering ◽  
Negative Ion ◽  
Resonance Mechanism ◽  
Resolution Electron ◽  
Surface Resonance ◽  
Surface Vibrations ◽  
Diffraction Patterns ◽  
Angular Diffraction ◽  
Electron Energy Loss

The surface vibrations of H-terminated Si(111) are investigated by high resolution electron energy loss spectroscopy (HREELS). Clear evidence is obtained for reassigning the electron resonant scattering from a surface resonance to a negative ion resonance mechanism. Since the electrons emitted from the trapping states show characteristic angular diffraction patterns realated with the geometric and vibrational symmetries of the surface, we suggest the possibility of using this system to investigate vibrationally resolved electron diffraction processes.

Application of High Spatial Resolution Electron Diffraction Techniques to the Study of Local Properties of Crystalline Solids

1994 ◽  
Vol 332 ◽  
Author(s):  
J W Steeds ◽  
X F Duan ◽  
P A Midgley ◽  
P Spellward ◽  
R Vincent
Keyword(s):  
Electron Diffraction ◽  
Spatial Resolution ◽  
Materials Science ◽  
High Spatial Resolution ◽  
High Quality ◽  
Resolution Electron ◽  
Electron Energy Loss Spectrometer ◽  
Local Properties ◽  
Diffraction Patterns ◽  
Electron Energy Loss

ABSTRACTThe addition of a Gatan imaging parallel electron-energy loss spectrometer (IPEELS) to a Hitachi HF 2000 cold field emission TEM has allowed us to produce high quality energy-filtered coherent electron diffraction patterns and electron holograms from a wide variety of materials. In this paper we review the recent achievements and make an assessment of the use of coherent electron diffraction in solving problems at high spatial resolution in materials science.

Anisotropic radiation damage of potassium tetracyano platinate (KCP)

1978 ◽  
Vol 36 (1) ◽  
pp. 392-393
Author(s):  
N. Uyeda ◽  
E. J. Kirkland ◽  
B. M. Siegel
Keyword(s):  
Electron Diffraction ◽  
Radiation Damage ◽  
Structural Changes ◽  
High Resolution Electron Microscopy ◽  
Radiation Sensitivity ◽  
Resolution Electron ◽  
Damage Process ◽  
Diffraction Patterns ◽  
Fading Rate

The direct observation of structural change by high resolution electron microscopy will be essential for the better understanding of the damage process and its mechanism. However, this approach still involves some difficulty in quantitative interpretation mostly being due to the quality of obtained images. Electron diffraction, using crystalline specimens, has been the method most frequently applied to obtain a comparison of radiation sensitivity of various materials on the quantitative base. If a series of single crystal patterns are obtained the fading rate of reflections during the damage process give good comparative measures. The electron diffraction patterns also render useful information concerning the structural changes in the crystal. In the present work, the radiation damage of potassium tetracyano-platinate was dealt with on the basis two dimensional observation of fading rates of diffraction spots. KCP is known as an ionic crystal which possesses “one dimensional” electronic properties and it would be of great interest to know if radiation damage proceeds in a strongly asymmetric manner.

A library of convergent-beam electron diffraction patterns

1986 ◽  
Vol 44 ◽  
pp. 688-691
Author(s):  
John F. Mansfield
Keyword(s):  
Electron Diffraction ◽  
Materials Science ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Transmission Electron ◽  
Yield Information ◽  
Analytical Electron ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Electron Energy Loss

One of the most important advancements of the transmission electron microscopy (TEM) in recent years has been the development of the analytical electron microscope (AEM). The microanalytical capabilities of AEMs are based on the three major techniques that have been refined in the last decade or so, namely, Convergent Beam Electron Diffraction (CBED), X-ray Energy Dispersive Spectroscopy (XEDS) and Electron Energy Loss Spectroscopy (EELS). Each of these techniques can yield information on the specimen under study that is not obtainable by any other means. However, it is when they are used in concert that they are most powerful. The application of CBED in materials science is not restricted to microanalysis. However, this is the area where it is most frequently employed. It is used specifically to the identification of the lattice-type, point and space group of phases present within a sample. The addition of chemical/elemental information from XEDS or EELS spectra to the diffraction data usually allows unique identification of a phase.

Atomic structure of YB56 studied by digital high-resolution electron microscopy and electron diffraction

2001 ◽  
Vol 16 (1) ◽  
pp. 101-107 ◽  
Author(s):  
Takeo Oku ◽  
Jan-Olov Bovin ◽  
Iwami Higashi ◽  
Takaho Tanaka ◽  
Yoshio Ishizawa
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Charge Coupled Device ◽  
X Ray ◽  
Resolution Electron ◽  
High Resolution Images ◽  
Diffraction Patterns ◽  
Simulated Images

Atomic positions for Y atoms were determined by using high-resolution electron microscopy and electron diffraction. A slow-scan charge-coupled device camera which had high linearity and electron sensitivity was used to record high-resolution images and electron diffraction patterns digitally. Crystallographic image processing was applied for image analysis, which provided more accurate, averaged Y atom positions. In addition, atomic disordering positions in YB56 were detected from the differential images between observed and simulated images based on x-ray data, which were B24 clusters around the Y-holes. The present work indicates that the structure analysis combined with digital high-resolution electron microscopy, electron diffraction, and differential images is useful for the evaluation of atomic positions and disordering in the boron-based crystals.

A Comparison of Electron Energy Loss Spectroscopy and Electron Diffraction for Polycrystalline and Xe+ Irradiated Nickel Silicides

1983 ◽  
Vol 25 ◽  
Author(s):  
J.C. Barbour ◽  
L.A. Grunes ◽  
J.W. Mayer
Keyword(s):  
Electron Diffraction ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Nickel Silicide ◽  
Core Level ◽  
Electronic Density ◽  
Peak Energy ◽  
Diffraction Patterns ◽  
Electron Energy Loss

ABSTRACTVariations in the valence and core level electron energy loss spectroscopy (EELS) peaks are studied as a function of nickel silicide composition.Analysis of the EELS spectra in comparison with the electron diffraction patterns show the plasmon energies fingerprint the silicide phases. The EELS core level spectra reflect the Si bonding and the electronic density of states in each phase.Irradiated Ni 2Si becomes amorphous causing a change in the plasmon peak energy and the Si L23peaks.

Small-Spot Illumination For High-Resolution Electron Microscopy of Beam-Sensitive Specimens

1985 ◽  
Vol 43 ◽  
pp. 320-321
Author(s):  
Kenneth H. Downing ◽  
Robert M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
High Resolution ◽  
Electron Diffraction ◽  
High Resolution Electron Microscopy ◽  
Photographic Emulsion ◽  
Lateral Motion ◽  
Small Spot ◽  
Resolution Electron ◽  
Diffraction Patterns

The contrast observed in images of beam-sensitive, crystalline specimens is found to be significantly less than one would predict based on observations of electron diffraction patterns of the specimens. Factors such as finite coherence, inelastic scattering, and the limited MTF of the photographic emulsion account for some decrease in contrast. It appears, however, that most of the loss in signal is caused by motion of the specimen during exposure to the electron beam. The introduction of point and other defects in the crystal, resulting from radiation damage, causes bending and lateral motion, which degrade the contrast in the image. We have therefore sought to determine whether the beam-induced specimen motion can be reduced by reducing the area of the specimen which is illuminated at any one time.

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