TILT ANGLE DETERMINATION OF A SMECTIC C-PHASE BY FIELD-INDUCED FREEDERICKSZ TRANSITION AND X-RAY-INVESTIGATIONS

A smectic liquid crystal exhibiting positive dielectric anisotropy was oriented with the director parallel to the glass substrates. When an electric field was applied normal to the director direction a dielectric reorientation (Fredericksz transition) occurred. Dissolving a dichroic dye in the smectic C phase and applying an electric field, a guest host effect similar to nematic phases was observed. From the dielectric reorientation the tilt angle of the smectic C phase was determined at different temperatures. The tilt angles obtained by the electrooptical measurements agree sufficiently with the values measured by X ray investigations.