STUDY BY FTIR SPECTROSCOPY OF THE REORIENTATION DYNAMIC OF A FERROELECTRIC LIQUID-CRYSTAL

The Fourier transform infrared (FTIR) electro-modulation technique has been used to study the reorientation dynamic, of a partly deuterated ferroelectric liquid crystal (le 10.S.ClIsoleu-D), induced by the appl ication of an alternative electric field. Two relaxation processes hav e been observed. They were connected with the collective switching of molecules in the smectic C and smectic A phases. The spectra analysis has shown that the molecular vibrators were switching with different reorientational motion amplitude in both phases but that their periodi c reorientation was coinciding in the ferroelectric phase whereas it w as desynchronizing in the smectic A phase.