Dielectric Relaxation and Quasielastic Neutron Scattering Study of Molecular Reorientation in the Nematic and Solid Phases of 4,4'-Di-N-Butyloxyazoxybenzene
作者:
K. Chłedowska,
D. Chruściel,
J.A. Janik,
J.M. Janik,
H. Kresse,
H. Stettin,
K. Otnes,
T. Stanek,
S. Urban,
S. Wróbel,
期刊:
Liquid Crystals
(Taylor Available online 1988)
卷期:
Volume 3,
issue 10
页码: 1339-1354
ISSN:0267-8292
年代: 1988
DOI:10.1080/02678298808086615
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Dielectric relaxation measurements carried out in the nematic phae of 4,4'-di-n-butyloxyazoxybenzene (BOAOB) reveal fast reorientational motions of the whole molecule around the long axis (τ1∼ 60 ps) as well as slow reorientational motions of the whole molecule around the short axis (τ1∼ 10−8s). Incoherent quasielastic neutron scattering spectra obtained for nematic BOAOB, with normal and deuteriated alkoxy terminals, are interpreted as dominated by reorientation (around the C-N bonds) of moieties consisting of benzene rings coupled with alkoxy terminal chains (τ1∼ 4ps). In addition fast conformational changes occur in these chains. Dielectric relaxation measurements reveal librations of the whole molecule in the crystal phases CI and CII accompanied by reorientation of the terminal chains in these phases. The reorientations occur on the time scale amounting to 10-8s. Incoherent quasielastic neutron scattering spectra obtained for the CI and CII phases of BOAOB are interpreted as being dominated by overdamped librational motions of the moieties accompanied by fast conformational changes in the alkyl chains. The CIII phase corresponds to a normal molecular crystal.
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