Two-dimensional nucleation according to an exponential law with surface diffusion-controlled growth in the phase formation of uracil on Au(hkl)

1997 ◽  
Vol 427 (1-2) ◽  
pp. 105-112 ◽  
Author(s):  
Th. Wandlowski ◽  
Th. Dretschkow
Keyword(s):  
Surface Diffusion ◽  
Phase Formation ◽  
Controlled Growth ◽  
Two Dimensional ◽  
Exponential Law ◽  
Diffusion Controlled

Numerical Simulation of Diffusion Controlled Surface Evolution

1993 ◽  
Vol 317 ◽  
Author(s):  
Cheng-Hsin Chiu ◽  
Huajian Gao
Keyword(s):  
Numerical Simulation ◽  
Numerical Methods ◽  
Diffusion Process ◽  
Surface Diffusion ◽  
Morphological Evolution ◽  
Two Dimensional ◽  
Lateral Direction ◽  
Surface Evolution ◽  
Diffusion Controlled ◽  
Heteroepitaxial Layers

ABSTRACTAs a model for Stranski-Krastanow island formation in strained heteroepitaxial layers, this paper investigates the surface-diffusion controlled morphological evolution of a two dimensional semi-infinite solid loaded in the lateral direction. Numerical Methods are developed to simulate the surface diffusion process, and examples are presented to demonstrate three distinct evolution patterns which are characterized by two critical wavelengths. The results show that, according to the wavelength, a slightly wavy surface can evolve into a cusped, a smoothly undulating, or a flat configuration. The diffusion wavelength and cusp-formation time compare favorably with recent experimental observations.

A linearity test for thick specimens imaged by HVEM over a 180° angular range

1991 ◽  
Vol 49 ◽  
pp. 552-553
Author(s):  
Yu Liu
Keyword(s):  
Phase Contrast ◽  
Three Dimensional ◽  
Angular Range ◽  
Two Dimensional ◽  
Back Projection ◽  
Line Integral ◽  
Exponential Law ◽  
Transmission Electron ◽  
Absorption Law ◽  
Linearity Test

The image obtained in a transmission electron microscope is the two-dimensional projection of a three-dimensional (3D) object. The 3D reconstruction of the object can be calculated from a series of projections by back-projection, but this algorithm assumes that the image is linearly related to a line integral of the object function. However, there are two kinds of contrast in electron microscopy, scattering and phase contrast, of which only the latter is linear with the optical density (OD) in the micrograph. Therefore the OD can be used as a measure of the projection only for thin specimens where phase contrast dominates the image. For thick specimens, where scattering contrast predominates, an exponential absorption law holds, and a logarithm of OD must be used. However, for large thicknesses, the simple exponential law might break down due to multiple and inelastic scattering.

Suppression of vigorous liquid Sn/Te reactions by Sn–Cu solder alloys

2008 ◽  
Vol 23 (12) ◽  
pp. 3303-3308 ◽  
Author(s):  
Chien-Neng Liao ◽  
Ching-Hua Lee
Keyword(s):  
Reaction Time ◽  
Layered Structure ◽  
Controlled Growth ◽  
Square Root ◽  
Solder Alloys ◽  
Cu Content ◽  
Cu Alloys ◽  
Diffusion Controlled ◽  
Morphology Changes

Reactions of molten Sn–xCu (x = 0.05 to 1.0) alloys with Te substrate at 250 °C were investigated. A dosage of 0.1 wt% Cu in Sn is found to be effective in suppressing the vigorous Sn/Te reaction by forming a thin CuTe at the solder/Te interface. The CuTe morphology changes from irregular clusters into a layered structure with increasing Cu content in Sn. With the same reaction time, the CuTe thickness increases proportionally to the square root of Cu content in Sn–Cu alloys, suggesting a diffusion-controlled growth for CuTe.

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