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Title: Structure of nanoscale-pitch helical phases: Blue phase and twist-bend nematic phase resolved by resonant soft X-ray scattering

Abstract

Periodic structures of phases with orientational order of molecules but homogenous electron density distribution: a short pitch cholesteric phase, blue phase and twist-bend nematic phase, were probed by resonant soft X-ray scattering (RSoXS) at the carbon K-edge. The theoretical model shows that in the case of a simple heliconical nematic structure, two resonant signals corresponding to the full and half pitch band should be present, while only the full pitch band is observed experimentally. This suggests that the twist-bend nematic phase has a complex structure with a double-helix built of two interlocked, shifted helices. We confirm that the helical pitch in the twist-bend nematic phase is in a 10 nm range for both the chiral and achiral materials. We also show that the symmetry of the blue phase can be unambiguously determined through a resonant enhancement of the X-ray diffraction signals, by including polarization effects, which are found to be an important indicator in phase structure determination.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3];  [4]; ORCiD logo [4]; ORCiD logo [3]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kent State Univ., Kent, OH (United States)
  2. Univ. of Maribor (Slovenia); Jozef Stefan Institute, Lubljana (Slovenia)
  3. Univ. of Warsaw (Poland)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1530276
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Soft Matter
Additional Journal Information:
Journal Volume: 13; Journal Issue: 38; Journal ID: ISSN 1744-683X
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Salamończyk, Mirosław, Vaupotič, Nataša, Pociecha, Damian, Wang, Cheng, Zhu, Chenhui, and Gorecka, Ewa. Structure of nanoscale-pitch helical phases: Blue phase and twist-bend nematic phase resolved by resonant soft X-ray scattering. United States: N. p., 2017. Web. doi:10.1039/c7sm00967d.
Salamończyk, Mirosław, Vaupotič, Nataša, Pociecha, Damian, Wang, Cheng, Zhu, Chenhui, & Gorecka, Ewa. Structure of nanoscale-pitch helical phases: Blue phase and twist-bend nematic phase resolved by resonant soft X-ray scattering. United States. https://doi.org/10.1039/c7sm00967d
Salamończyk, Mirosław, Vaupotič, Nataša, Pociecha, Damian, Wang, Cheng, Zhu, Chenhui, and Gorecka, Ewa. Fri . "Structure of nanoscale-pitch helical phases: Blue phase and twist-bend nematic phase resolved by resonant soft X-ray scattering". United States. https://doi.org/10.1039/c7sm00967d. https://www.osti.gov/servlets/purl/1530276.
@article{osti_1530276,
title = {Structure of nanoscale-pitch helical phases: Blue phase and twist-bend nematic phase resolved by resonant soft X-ray scattering},
author = {Salamończyk, Mirosław and Vaupotič, Nataša and Pociecha, Damian and Wang, Cheng and Zhu, Chenhui and Gorecka, Ewa},
abstractNote = {Periodic structures of phases with orientational order of molecules but homogenous electron density distribution: a short pitch cholesteric phase, blue phase and twist-bend nematic phase, were probed by resonant soft X-ray scattering (RSoXS) at the carbon K-edge. The theoretical model shows that in the case of a simple heliconical nematic structure, two resonant signals corresponding to the full and half pitch band should be present, while only the full pitch band is observed experimentally. This suggests that the twist-bend nematic phase has a complex structure with a double-helix built of two interlocked, shifted helices. We confirm that the helical pitch in the twist-bend nematic phase is in a 10 nm range for both the chiral and achiral materials. We also show that the symmetry of the blue phase can be unambiguously determined through a resonant enhancement of the X-ray diffraction signals, by including polarization effects, which are found to be an important indicator in phase structure determination.},
doi = {10.1039/c7sm00967d},
url = {https://www.osti.gov/biblio/1530276}, journal = {Soft Matter},
issn = {1744-683X},
number = 38,
volume = 13,
place = {United States},
year = {2017},
month = {8}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 35 works
Citation information provided by
Web of Science

Figures / Tables:

Figure 1 Figure 1: Structure of the (a) twist-bend nematic N TB, (b) chiral nematic N*, (c) splaybend nematic N SB. L is a modulation length. Double twisted cylinders (left) and the defect network (right) in blue phases (d) of type I (BPI) and (e) type II (BPII).

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Works referenced in this record:

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    Works referencing / citing this record:

    Pretransitional behavior of viscoelastic parameters at the nematic to twist-bend nematic phase transition in flexible n -mers
    journal, January 2019


    Pretransitional behavior of viscoelastic parameters at the nematic to twist-bend nematic phase transition in flexible n -mers
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    The Chiral Twist‐Bend Nematic Phase (N* TB )
    journal, September 2019


    Twist-bend nematic phase in biphenylethane-based copolyethers
    journal, January 2018


    Dynamic calorimetry and XRD studies of the nematic and twist-bend nematic phase transitions in a series of dimers with increasing spacer length
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    Twist-bend nematic liquid crystals based on thioether linkage
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    Supramolecular organization of liquid-crystal dimers – bis-cyanobiphenyl alkanes on HOPG by scanning tunneling microscopy
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    Optically active bimesogens incorporating branched central spacers
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    Double helical structure of the twist-bend nematic phase investigated by resonant X-ray scattering at the carbon and sulfur K-edges
    journal, January 2018


    Indication of a twist-grain-boundary-twist-bend phase of flexible core bent-shape chiral dimers
    journal, January 2019


    Macroscopic chirality of twist-bend nematic phase in bent dimers confirmed by circular dichroism
    journal, January 2020


    Controlling the formation of heliconical smectic phases by molecular design of achiral bent-core molecules
    journal, January 2020


    Dielectric response of electric-field distortions of the twist-bend nematic phase for LC dimers
    journal, September 2019


    Distinct differences in the nanoscale behaviors of the twist–bend liquid crystal phase of a flexible linear trimer and homologous dimer
    journal, May 2019


    The induction of the N tb phase in mixtures
    journal, September 2018


    Uniform distortions and generalized elasticity of liquid crystals
    journal, November 2019


    Coarse-grained model of the nematic twist-bend phase from a stable state elastic energy
    journal, January 2020


    Liquid crystal distortions revealed by an octupolar tensor
    journal, January 2020


    Chiral Incommensurate Helical Phase in a Smectic of Achiral Bent-Core Mesogens
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    Physics of liquid crystals of bent-shaped molecules
    journal, November 2018


      Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.