کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5402353 | 1392732 | 2010 | 8 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Low-temperature photoluminescence of 5CB liquid crystal
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موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی تئوریک و عملی
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چکیده انگلیسی
The photoluminescence spectra of the 4-n-pentyl-4â²-cyanobiphenyl (5CB) liquid crystal have been investigated in detail at low temperatures 4.2-200 K, for the first time. The spectral data obtained are compared to the results of the luminescence study for the 5CB nematic phase at Т=300 K. The luminescence of the 5CB crystal state is characterized by emissions of both monomer and dimer structures. Besides, there are several energetically and conformationally non-equivalent types of monomers and dimers, and their amounts change with the temperature growth non-monotonously. The 5CB several crystal modifications, having different 5CB monomer and dimer conformers, have been found out below T=160 K. The 5CB crystal-crystal transition at Т=80 K is characterized with a total loss of the fine structure in the 5CB photoluminescence spectrum and a disappearance of the spectral band at 343 nm. At T=140 K, a new spectral band at 424 nm appears; it corresponds to the significantly overlapping 5CB dimers, its intensity grows under further heating. The present investigation gives a tool for the further characterization of the molecular alignments and changes in the 5CB molecular conformations, using the monomer and excimer fluorescence emissions as a probe. The conclusions made are confirmed by the IR-spectroscopy data, measured and analyzed for the 5CB in the same temperature region.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Luminescence - Volume 130, Issue 7, July 2010, Pages 1134-1141
Journal: Journal of Luminescence - Volume 130, Issue 7, July 2010, Pages 1134-1141
نویسندگان
T. Bezrodna, V. Melnyk, V. Vorobjev, G. Puchkovska,