Anisotropic Change of Liquid-Crystal Domains by Polarized Infrared Pulse Laser Irradiation for a Columnar Mesophase


  • We gratefully acknowledge the financial support of Ministry of Economy, Trade and Industry (METI). We thank Mr. Shoichiro Kuma, and Mr. Mikio Tanaka for their support in operating the FEL facilities, We also thank Mr. Yoshihiro Setoguchi for his support in preparing the materials.


The infrared photoinduced alignment change of liquid-crystal domains was investigated for a hexagonal columnar mesophase of a liquid-crystalline triphenylene derivative. A uniform and anisotropic alignment change of domains was observed when a polarized infrared (IR) light corresponding to the wavelength of the aromatic C–C stretching absorption band of the triphenylene core was used to irradiate the sample. The relationship between the aligned azimuthal angle of the columnar axis and the polarization of the IR incident irradiation was investigated. IR absorption dichroism is induced as a result of the reorientation of triphenylene core. Texture observation and polarizing microscope FTIR spectra show that a change of the molecular alignment occurred and that the direction of columns depends on the polarization angle of the IR light used for irradiation. The mechanism of the alignment change in a columnar liquid crystal film by IR irradiation is also discussed. The technique could provide a novel technology to control the columnar alignment of highly viscous liquid crystals.