title: Polar structure in a ferroelectric bent-core mesogen as studied by second-harmonic generation.
abstract: Second-harmonic generation (SHG) measurements have been conducted in the ferroelectric liquid crystalline phase of a chiral bent-core molecule, P-8-OPIMB6*. Well-aligned cells were obtained by applying an electric field parallel to the substrate surfaces. In-plane anisotropy of the SHG signal observed at normal incidence of light shows two- or four-leaf patterns depending on polarization conditions, indicating a ferroelectric uniform structure. The detailed analysis of the data by taking account of optical anisotropy in the SHG active bulk leads to the determination of nonlinear susceptibility tensor components, d(333)=14.4 pm/V and d(311)=49.2 pm/V. Using the d coefficients thus determined, the hyperpolarizability tensor components of the molecule are also determined as beta(zzz)=14.5 x 10(-30) esu and beta(zxx)=67.6 x 10(-30) esu. These values well agree with those of the achiral homolog P-12-OPIMB previously determined by hyper-Rayleigh scattering.
authors.affiliation: Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro-ku, Tokyo 152-8552, Japan.
authors.forename: Fumito
authors.initials: F
authors.lastname: Araoka
authors.forename: Jirakorn
authors.initials: J
authors.lastname: Thisayukta
authors.forename: Ken
authors.initials: K
authors.lastname: Ishikawa
authors.forename: Junji
authors.initials: J
authors.lastname: Watanabe
authors.forename: Hideo
authors.initials: H
authors.lastname: Takezoe