Coexistence of polar and nonpolar domains and their photocontrol in the B7 phase of a bent-core liquid crystal containing azo dyes.
Coexisting polar and nonpolar domains have been studied by means of texture observation, x-ray analysis, optical second-harmonic generation (SHG), and SHG microscopy in the B7 phase of a bent-core mesogen doped with azo dyes. The bent-core molecules take a planar orientation and show high birefringence in the polar domain, while they take a homeotropic orientation and show low birefringence in the nonpolar domain. Good correspondence between real and SHG images was observed under a SHG microscope; the bright (high-birefringent) domain is SHG active and the dark (low-birefringent) domain is not SHG active. Photoisomerization of the azo dyes causes layer reorientation from the layer perpendicular to the substrate to that parallel to it.
Kim
Heekyung
H
Department of Physics, Korea University, Seoul 136, Korea.
Lim
Tong Kun
TK
Shin
Sung Tae
ST
Lee
Chong Kwang
CK
Araoka
Fumito
F
Ofuji
Masato
M
Takanishi
Yoichi
Y
Takezoe
Hideo
H