Anisometric molecules in dense fluids

Abstract

The Kerr constant of anisometric non-polar molecules in solvents of spherical molecules is calculated using the model of an ellipsoidal cavity in an isotropic dielectric continuum. It is shown that the Kerr constants has the same form as for dilute gases:

provided that effective polarizability elements α _xx ^l * (optical) and α _xx ^s * (static) replace the vacuum values α _xx ^l and α _xx ^s in Γ*, which then reads Γ* = 1/2[(α _xx ^l * - α _yy ^l *)(α _xx ^s *) - α _yy ^s *) + circular permutation].

Each effective polarizability element α _xx * (either optical or static) is composed of two contributions, one pertaining to the anisometric solute itself and another arising from the anisotropic distortion of the polarization in the neighbouring continuum. These two contributions are of opposite signs, so that large variations of the magnitude of the Kerr effect are predicted, depending essentially upon the mean refractivity and permittivity of the solute compared with those of the solvent.