Second Kerr effect virial coefficients of polar molecules with linear and lower symmetry

An overview is given of theoretical and experimental work undertaken on the second Kerr effect virial coefficient B-K, and a new molecular tensor theory of B-K for molecules of nonlinear symmetry is presented. The theory is general, and includes molecules of higher symmetry as special cases. Calculated values for the polar axially symmetric molecules fluoromethane and trifluoromethane reveal good agreement with experiment, although the large uncertainties of +/-50% in the measured data do not provide a stringent test of the theory. Values of B-K calculated for the nonlinear polar molecules sulphur dioxide, difluoromethane and dimethyl ether over a range of temperatures generally are within the uncertainty limits of the experimental values quoted in the literature.