Pattern Center and Distortion Determined from Faint, Diffuse Electron Diffraction Rings from Amorphous Materials.

Area of Science:

• Materials Science
• Crystallography
• Data Analysis

Background:

• Diffuse rings from amorphous materials often present weak intensity on a steep background, lacking clear maxima for accurate analysis.
• Traditional methods struggle with monotonically decreasing intensity profiles and identifying the precise center of these diffuse patterns.

Purpose of the Study:

• To develop and validate a novel method for processing weak, diffuse ring patterns from amorphous materials.
• To enable accurate determination of pattern center and elliptical distortion from challenging experimental data.

Main Methods:

• Separating the angular dependence of peak maxima on azimuthal angle in 2D patterns.
• Simultaneously refining pattern center and elliptical distortion using nonlinear least square fitting (Levenberg-Marquardt).
• Accumulating data from multiple patterns and masking unwanted regions to enhance signal-to-noise ratio and mitigate artifacts.

Main Results:

• Successful processing of weak, diffuse ring patterns previously difficult to analyze.
• Accurate determination of pattern center and elliptical distortion, even for patterns with shifted centers (e.g., quadrants).
• Robustness demonstrated across various amorphous materials and experimental conditions facilitating sector analysis.

Conclusions:

• The developed method offers a reliable approach for analyzing weak diffuse ring patterns from amorphous materials.
• This technique enhances the ability to extract structural information from challenging scattering data.
• Applicable to a wide range of amorphous materials when experimental conditions permit sectoral analysis.