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Relationship between the distortion of polyene chains from planarity and the Raman activity of the in‐phase CH out‐of‐plane wag
Author(s) -
Fujimori Kazuki,
Sakamoto Akira,
Tasumi Mitsuo
Publication year - 2004
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200450104
Subject(s) - polyene , raman spectroscopy , planarity testing , distortion (music) , phase (matter) , molecule , chemistry , molecular physics , computational chemistry , infrared , crystallography , materials science , physics , optics , organic chemistry , amplifier , optoelectronics , cmos
The relationship between the distortion of polyene chains from planarity and the Raman activity of the in‐phase CH out‐of‐plane wag is examined by performing density functional theory calculations. The vibrational wavenumbers, vibrational modes, Raman activities and infrared absorption intensities of several oligoene (or polyene) molecules are calculated for model structures having various kinds of distortion around the CC double and/or single bond(s). The results of calculations show that the molecular distortion induces the Raman activity of the in‐phase CH out‐of‐plane wag which should be Raman‐inactive for the planar structure. The Raman activity of the in‐phase CH out‐of‐plane wag is particularly enhanced when the molecule is uniformly helical. The origin of a weak Raman band at about 1010 cm −1 of trans ‐polyacetylene is discussed on the basis of the calculated results.