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Updated: Jun 4, 2025

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Mapping the local ambidextrous chirality in thin films of NTB phase by circular dichroism spectra
Huanan Yu1, Chris Welch2, Georg H Mehl2
1School of Materials and Chemistry, China Jiliang University, Hangzhou 310018, China.
Abstract:
Circular dichroism mapping (CDM) method was introduced by utilizing the highly collimated light beam of synchrotron radiation (SR) available at Diamond Light Source B23 beamline for scanning the thin films of the NTB phase. We apply SR-CDM to two achiral dimeric materials exhibiting the NTB phase: symmetric DTC5C9 and dissymmetric DTC5C9CB. The SR-CDM measurements directly capture the chiral information in the local NTB domains, providing the ultimate complement to the theoretical predictions of the helical structures: the spontaneous symmetry breaking in NTB phase is ambidextrous. The macroscopic chirality of the NTB phase is determined by the combination of doubly degenerate locally chiral domains in the illuminated area. Additionally, we investigate the temperature dependence, as well as the dynamic nature of the local chirality in the NTB phase by in-situ SR-CDM, confirming a chiral conversion influenced by the state of enantiomeric aggregation and a progressive unwinding of the helical structure in left-handed domains as the crystallization temperature is approached.
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