On the peculiarities of CBED pattern formation revealed by multislice simulation

Area of Science:

• Materials Science
• Solid State Physics
• Crystallography

Background:

• Convergent Beam Electron Diffraction (CBED) is crucial for materials characterization.
• Accurate simulation of CBED patterns, especially Higher-Order Laue Zone (HOLZ) lines, is essential for detailed analysis.
• Existing methods may have limitations in fully capturing the complexities of CBED pattern formation.

Purpose of the Study:

• To develop and validate a modified multislice method for CBED pattern calculations.
• To gain a deeper understanding of the formation mechanisms of CBED patterns, focusing on HOLZ and Kikuchi lines.
• To investigate the role of dynamical scattering in HOLZ reflections and their influence on the central CBED disk.

Main Methods:

• Development of a modified multislice computational method for CBED pattern simulation.
• Validation of the method by comparing HOLZ- and Kikuchi-line calculations against established Bloch-wave calculations.
• Analysis of the scattering areas associated with different HOLZ lines and their impact on the central disk.

Main Results:

• The modified multislice method accurately reproduces HOLZ- and Kikuchi-line patterns, confirming its validity.
• Dynamical scattering of weak HOLZ reflections is identified as the primary cause of deficient lines in the central CBED disk.
• The central CBED disk integrates structural information from a sample region determined by HOLZ Bragg angles and thickness.

Conclusions:

• The developed method provides new insights into the formation of CBED patterns.
• Variations in lattice parameters within the probed area lead to artificial symmetry violations and altered line profiles.
• This enhanced understanding facilitates more precise materials analysis using CBED.