Study of liquid crystal space groups using controlled tilting with cryogenic transmission electron microscopy

Area of Science:

• Materials Science
• Crystallography
• Electron Microscopy

Background:

• Liquid crystalline phases exhibit diverse structures with distinct space groups.
• Differentiating between these structures is crucial for understanding their properties and applications.
• Current methods may lack the resolution or specificity for unambiguous identification.

Purpose of the Study:

• To develop a reliable method for distinguishing liquid crystalline-phase particles based on their space groups.
• To enable unambiguous identification of specific inverted cubic and bicontinuous liquid crystalline structures.

Main Methods:

• Utilizing cryogenic transmission electron microscopy (cryo-TEM).
• Implementing controlled specimen tilting to observe particles from multiple orientations.
• Analyzing the presence or absence of specific lattice planes (reflections) in different orientations.

Main Results:

• The method successfully differentiates between liquid crystalline particles corresponding to different space groups.
• Specific lattice planes were identified that are unique to each analyzed structure.
• Unambiguous distinction was achieved among inverted micellar cubic (Fd(3)m), inverted bicontinuous gyroid (Ia(3)d), inverted bicontinuous diamond (Pn(3)m), and primitive cubic (Im(3)m) structures.

Conclusions:

• Controlled tilting in cryo-TEM provides a powerful tool for liquid crystal structure determination.
• This technique offers a definitive way to assign space groups to liquid crystalline particles.
• The findings advance the characterization of complex soft matter systems.