Resonance mode and pretransitional fluctuations near the SmA-SmC* phase transition

A low-frequency (0.1 - 100 kHz) resonance mode interpreted as a texture one has been investigated on ferroelectric liquid crystals (FLC). Compounds an d mixtures showing different types of the phase transition into the SmC* ph ase (I - SmC*, N* - SmC*, SmA - SmC*) have been examined in order to find t he resonance properties in the ferroelectric phase. It has been shown that the origin of the resonance response (resonance mode) is caused by strong p retransitional order parameter fluctuations in both SmA and SmC* phases nea r the second order SmA - SmC* phase transition. The principal factor causin g the resonance made origination is the presence of an external mechanical field in the well aligned uniform bookshelf FLC texture. An interaction bet ween the texture resonance mode and bending modes of glass cell plates and the synchronization effect have been investigated.