Premium
Non‐linear Raman spectroscopy of liquid crystals: Polarization measurements and relaxation processes in 4‐cyano‐4′‐heptylbiphenyl (7CB)
Author(s) -
Davies A. N.,
Jeremy Jones W.,
Price Alun H.
Publication year - 1994
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250250713
Subject(s) - raman spectroscopy , anisotropy , polarization (electrochemistry) , depolarization ratio , chemistry , molecule , liquid crystal , relaxation (psychology) , analytical chemistry (journal) , spectroscopy , linear molecular geometry , molecular physics , nuclear magnetic resonance , materials science , condensed matter physics , optics , physics , organic chemistry , psychology , social psychology , quantum mechanics
The non‐linear Raman spectrum of 4‐cyano‐4′‐heptylbiphenyl is reported. Measurements of depolarization ratios of the vibrational bands at 2224 cm −1 (CN stretching), 1606 cm −1 (aromatic ring stretching) and 1185 cm −1 (CH aromatic in‐plane deformation) are used to evaluate the order parameters (〈 P 2 〉 and 〈 P 4 〉) using a ‘line model’ for the molecules. The results are internally consistent and also show the same general features (including some discrepancies in 〈 P 4 〉) reported by other workers. Nevertheless, the results demonstrate that the technique is capable of wide application to the study of the anisotropic properties of liquid crystals and provides a valuable probe into the study of the biaxial nature of these sytems.