Assignment of enantiomorphs for the chiral allotrope β-Mn by diffraction methods

Area of Science:

• Materials Science
• Crystallography
• Solid-State Physics

Background:

• Determining the absolute configuration of chiral crystals is crucial in materials science.
• Traditional X-ray diffraction methods face limitations in assigning enantiomorphs for certain materials, such as the chiral allotrope of beta-manganese (β-Mn).
• Electron diffraction offers an alternative but requires careful consideration of dynamical effects for enantiomeric differentiation.

Purpose of the Study:

• To investigate the fundamental differences between X-ray and electron diffraction for enantiomorph assignment.
• To develop and apply a method for spatially resolved chirality determination in polycrystalline β-Mn and related phases.
• To compare the efficacy of electron diffraction with X-ray diffraction for distinguishing enantiomers.

Main Methods:

• Kikuchi pattern simulation was employed, considering dynamical electron diffraction, to differentiate between enantiomorphs.
• Quantitative comparison of experimental and simulated Kikuchi patterns was performed.
• Micropreparation techniques were used to extract crystals from enantiopure domains identified via enantiomorph distribution maps.

Main Results:

• Electron diffraction, particularly when considering dynamical effects, reveals distinguishable Kikuchi patterns for β-Mn enantiomorphs.
• Spatially resolved enantiomorph assignment was successfully achieved for polycrystalline β-Mn and the related phase Pt₂Cu₃B.
• X-ray diffraction confirmed the enantiomorph assignments for Pt₂Cu₃B but could not differentiate between β-Mn enantiomorphs.

Conclusions:

• Dynamical electron diffraction provides a viable method for assigning enantiomorphs in materials where X-ray diffraction is insufficient.
• The developed electron diffraction approach enables precise, spatially resolved chirality determination in complex polycrystalline materials.
• This technique advances the characterization of chiral materials, facilitating further research and application.