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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) (SC-22)
OSTI Identifier:
1530276
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
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. doi: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. doi: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},
journal = {Soft Matter},
number = 38,
volume = 13,
place = {United States},
year = {2017},
month = {8}
}

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Works referenced in this record:

Chiral heliconical ground state of nanoscale pitch in a nematic liquid crystal of achiral molecular dimers
journal, September 2013

  • Chen, D.; Porada, J. H.; Hooper, J. B.
  • Proceedings of the National Academy of Sciences, Vol. 110, Issue 40, p. 15931-15936
  • DOI: 10.1073/pnas.1314654110