Orientation of liquid crystalline 5CB under an external electric field

The orientation characteristics of pre-aligned liquid crystalline 5CB (4-n- pentyl-4'-cyanobiphenyl) in a germanium cell with unidirectional rubbed pol yimide-coated surfaces have been investigated. Orientation of 5CB molecules near the polyimide surface and those representing average properties of th e system (i.e., the bulk) are compared. The orientation of the bulk is moni tored by transmission Fourier transform infrared (FT-IR) spectroscopy while that of the molecules next to the surface is observed via attenuated total reflection (ATR) FT-IR spectroscopy. There are significant differences in orientation characteristics between the two groups of molecules. For molecu les near the polyimide surface, there is an observable difference in orient ation of the soft and hard segments of the liquid crystalline. Moreover, th ey show depth dependent orientation. (C) 1999 Elsevier Science B.V. All rig hts reserved.