Molecular ordering in a biaxial smectic-A phase studied byscanning transmission X-ray microscopy (STXM)
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.
- Research Organization:
- COLLABORATION - U.Saskatchewan/Canada
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 928443
- Report Number(s):
- LBNL-63068; R&D Project: A58130; BnR: KC0204016; TRN: US0804214
- Journal Information:
- Physical Chemistry Chemical Physics, Vol. 9, Issue 14; Related Information: Journal Publication Date: 25 January,2007; ISSN 1463-9076
- Country of Publication:
- United States
- Language:
- English
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