Magnetic susceptibility studies on a lyotropic nematic system

Abstract

We have carried out magnetic susceptibility studies on a lyotropic system, cesium perfluorooctanoate (CsPFO) in water for various concentrations of CsPFO. This system exhibits isotropic, nematic and lamellar phases on cooling for a range of concentrations. The structural unit in all the three phases is a disk shaped micelle with positive diamagnetic anisotropy. We find small discontinuous jumps in the magnetic susceptibility values in the vicinity of the isotropic-nematic transition temperatures for various concentrations. The susceptibility decreases initially with increasing CsPFO concentration and then increases. These observed changes can be attributed to the changes in the sizes and shapes of the micelles. We have also studied the temperature dependence of the diamagnetic anisotropy in the nematic phase. We discuss our results with those reported in the literature for lyotropic systems.