Modified multislice theory for calculating the energy-filtered inelastic images in REM and HREM

1989 ◽  
Vol 45 (2) ◽  
pp. 193-199 ◽  
Author(s):  
Z. L. Wang
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Diffuse Scattering ◽  
Transmission Function ◽  
High Resolution Electron Microscopy ◽  
Image Simulation ◽  
Resolution Electron ◽  
Electron Intensity ◽  
Reflection Electron Microscopy ◽  
Dependent Potential

Inelastic plasmon diffuse scattering (PDS) is treated as an effective position-dependent potential perturbing the incident electron wavelength in a solid surface, resulting in an extra phase grating term in the slice transmission function. This potential is derived for the geometry of reflection electron microscopy (REM) and high-resolution electron microscopy (HREM). The energy-filtered inelastic images can be calculated following the routine image simulation procedures by using different slice transmission functions for the elastic and inelastic waves, by considering the 'transitions' of the elastic scattered electrons to the inelastic scattered electrons. It is predicted that the inelastic scattering could modify the electron intensity distribution at a surface. It is possible to take high-resolution energy-filtered inelastic images of crystals, the resolution of which is about the same as that taken from the elastic scattered electrons.

Modified multislice theory for calculating the energy-filtered inelastic images in REM and HREM

1988 ◽  
Vol 46 ◽  
pp. 818-819
Author(s):  
Z. L. Wang
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Diffuse Scattering ◽  
High Resolution Electron Microscopy ◽  
Plasmon Excitation ◽  
Dynamical Calculation ◽  
Resolution Electron ◽  
Electron Intensity ◽  
Reflection Electron Microscopy ◽  
Image Position

Using a method introduced by Wang, the multiple plasmon diffuse scattering (PDS) can be included in dynamical calculation for reflection electron microscopy (REM) and high resolution electron microscopy (HREM). The calculated electron intensity distribution would be the combination of elastic and inelastic scattered electrons. In some experimental cases, it is desirable that the energy filtered inelastic image (EFIM) could be simulated. The purpose of this paper is to suggest a modified multislice theory for calculating the EFIM in REM and HREM.Considering an electron travelling in medium b with distance x parallel to an interface from medium a, due to the plasmon excitation, the wavelength of the electron is perturbed by its energy-loss during the propagation. The modified phase grating function (PGF) of a thin potential slice ▵z might be written as [1]:(1a)with(1b)

High resolution observations of short-range ordering in disordered Au4Mn alloys

1984 ◽  
Vol 42 ◽  
pp. 426-427
Author(s):  
Nobuo Tanaka ◽  
Ken-ichi Ohshima ◽  
Jinpei Harada ◽  
J.M. Cowley
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Diffuse Scattering ◽  
Short Range ◽  
High Resolution Electron Microscopy ◽  
Atomic Level ◽  
X Ray ◽  
Direct Observations ◽  
Resolution Electron ◽  
Short Range Ordering

Observation of short range ordered (SRO) state in disordered binary alloys is the interesting topic in the point of order-disorder transition. The observation and analysis have been made with X-ray and neutron diffraction techniques which can give the SRO-parameters. These techniques, however, give only the information of an averaged structure. The ordering process is localized, so direct observations in atomic level by high resolution electron microscopy is needed for the detailed analysis.In the present study, disordered Au4Mn alloys were investigated with high resolution electron microscopy for the analysis of the origin of the characteristic SRO diffuse scattering (Fig. 1). The material was prepared by quenching and thinned by electrolytic polishing for microscopic observations. The specimen was observed along <120> direction by JEOL-200CX electron microscope (E=200keV).

The Atomic Structure of Mosaïc Grain Boundary Dislocations in GaN Epitaxial Layers

1999 ◽  
Vol 589 ◽  
Author(s):  
V. Potin ◽  
G. Nouet ◽  
P. Ruterana ◽  
R.C. Pond
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Anisotropic Elasticity ◽  
Epitaxial Layers ◽  
Threading Dislocations ◽  
Image Simulation ◽  
Resolution Electron

AbstractThe studied GaN layers are made of mosaYc grains rotated around the c-axis by angles in the range 0-25°. Using high-resolution electron microscopy, anisotropic elasticity calculations and image simulation, we have analyzed the atomic structure of the edge threading dislocations. Here, we present an analysis of the Σ = 7 boundary using circuit mapping in order to define the Burgers vectors of the primary and secondary dislocations. The atomic structure of the primary ones was found to exhibit 5/7 and 8 atom cycles.

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