Textural and electrooptical investigations of the HOBA and OOBA cholesteric phases induced by chiral dopants

Optical and electrooptical properties of chiral dopants induced by cholesteric phase in 7 and 8 homologues (HOBA and OOBA) of the 4-n-alkyloxybenzoic acid are studied. A temperature Tp is found, where some anomalies in the electrooptical characteristics, the helix pitch of the system and a strong textural transformation, are detected. Similar to the nematic with smectic ordering, this temperature divides the induced cholesteric phase in two ranges with different characteristics. An electrooptical memorization of the fingerprint texture is found above Tp but not below Tp. The shift of the temperature Tp is investigated.