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Title: Molecular ordering in a biaxial smectic-A phase studied byscanning transmission X-ray microscopy (STXM)

Abstract

Results of STXM investigations of a binary mixture (1-TNF =2 :1; SmAb 140 M 180 Iso) known to form a SmAb phase [T. Hegmann, J.Kain, S. Diele, G. Pelzl and C. Tschierske, Angew. Chem. Int. Ed., 2001,40, 887]are presented. Near edge X-ray absorption fine spectra (NEXAFS)of the 1-TNF board-like aggregates, in particular the intensity of thelow energy peaks associated with aromatic ring * orbitals (284.5 286.5eV), show that the molecular plane of these aggregates is very sensitiveto the relative orientation of electric field vector E of linearlypolarized light, which is used to determine the molecular orientation inthe LC phase. The observed strong in-plane dichroic signal suggests thepredominant orientation of the 1-TNF aggregates to be along the smecticlayer normal as well as long-range ordering of the in-plane molecularorientation (biaxiality). Orientational maps derived from series ofmeasurements at different sample rotation angles around the specimennormal clearly show a Schlieren-type texture, and permit a detailedexamination of exclusive +-1/2 disclination theoretically predicted forthe SmAb phase.

Authors:
;
Publication Date:
Research Org.:
COLLABORATION - U.Saskatchewan/Canada
OSTI Identifier:
928443
Report Number(s):
LBNL-63068
Journal ID: ISSN 1463-9076; R&D Project: A58130; BnR: KC0204016; TRN: US0804214
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Chemistry Chemical Physics; Journal Volume: 9; Journal Issue: 14; Related Information: Journal Publication Date: 25 January,2007
Country of Publication:
United States
Language:
English
Subject:
37; 74; ABSORPTION; AROMATICS; BINARY MIXTURES; ELECTRIC FIELDS; MICROSCOPY; ORIENTATION; ROTATION; SPECTRA; TEXTURE; VECTORS; STXM Binary Smectic liquid Crystalline

Citation Formats

Kaznacheev, Konstaintin, and Hegmann, Torsten. Molecular ordering in a biaxial smectic-A phase studied byscanning transmission X-ray microscopy (STXM). United States: N. p., 2007. Web. doi:10.1039/b616010g.
Kaznacheev, Konstaintin, & Hegmann, Torsten. Molecular ordering in a biaxial smectic-A phase studied byscanning transmission X-ray microscopy (STXM). United States. doi:10.1039/b616010g.
Kaznacheev, Konstaintin, and Hegmann, Torsten. Thu . "Molecular ordering in a biaxial smectic-A phase studied byscanning transmission X-ray microscopy (STXM)". United States. doi:10.1039/b616010g.
@article{osti_928443,
title = {Molecular ordering in a biaxial smectic-A phase studied byscanning transmission X-ray microscopy (STXM)},
author = {Kaznacheev, Konstaintin and Hegmann, Torsten},
abstractNote = {Results of STXM investigations of a binary mixture (1-TNF =2 :1; SmAb 140 M 180 Iso) known to form a SmAb phase [T. Hegmann, J.Kain, S. Diele, G. Pelzl and C. Tschierske, Angew. Chem. Int. Ed., 2001,40, 887]are presented. Near edge X-ray absorption fine spectra (NEXAFS)of the 1-TNF board-like aggregates, in particular the intensity of thelow energy peaks associated with aromatic ring * orbitals (284.5 286.5eV), show that the molecular plane of these aggregates is very sensitiveto the relative orientation of electric field vector E of linearlypolarized light, which is used to determine the molecular orientation inthe LC phase. The observed strong in-plane dichroic signal suggests thepredominant orientation of the 1-TNF aggregates to be along the smecticlayer normal as well as long-range ordering of the in-plane molecularorientation (biaxiality). Orientational maps derived from series ofmeasurements at different sample rotation angles around the specimennormal clearly show a Schlieren-type texture, and permit a detailedexamination of exclusive +-1/2 disclination theoretically predicted forthe SmAb phase.},
doi = {10.1039/b616010g},
journal = {Physical Chemistry Chemical Physics},
number = 14,
volume = 9,
place = {United States},
year = {Thu Jan 25 00:00:00 EST 2007},
month = {Thu Jan 25 00:00:00 EST 2007}
}