Cotton—Mouton coefficient

Fig. 2.5.2. Reciprocal of the Cotton-Mouton coefficient in the isotropic phase of MBBA for two samples, one slightly impure and having a lower transition point 7J . Both yield the same value of 7J, —r = 1 C. (After Stinson and Litster.< >)...

The quantity An/lP is called the Cotton-Mouton coefficient which is seen to diverge at T = Tc and to fall off as (T — Tc )" above Tc. Measurements of magnetic birefringence have been made for MBBA, and the inverse Cotton-Mouton coefficient was plotted as a function of temperature. The experimental behavior is in complete agreement with Eq. [127]. Analysis of the data yields Tc Tc — 1 K. 

Cotton-Mouton effect), NMR chemical shift and coupling constants, the optical rotation of polarized light and correlation coefficients between different properties. Extensions to incorporate long-range interactions have also been elaborated11 and it has even been possible to adapt RIS theory for the description of the dynamics of transitions between rotational isomeric states.12,13... 

It is a special layer formation susceptibility close to the phase transition the nematic is very sensitive to the spatially periodic molecular field, which induce the density wave with period 1. In order to study this phenomenon one is tempted to use an external spatially periodic force with the same period, but, at present, it is technically impossible. Therefore, we cannot find the Landau coefficient a above T va using some analogy with the Kerr or Cotton-Mouton effects. 

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