Alignment-induced shift

Key Words Solid-state C NMR, Liquid crystal. Alignment-induced shift. Banana liquid... 

The former, in order to observe finite shifts of the equilibrium between two different polar states and the second superimposed a.c. field serves to measure the expected dielectric loss increments (produced by the field induced shift of the chemical equilibrium). Also, loss decrements are observed due to the considerable alignment of the particles in the high static field which alters the Boltzmann distribution. If both of these effects (which possess opposite signs) occur in the same frequency region, they will be superimposed on each other. Hence, the total dielectric loss is given by... 

Auzinsh, M., A.V. Stolyarov, M. Tamanis, and R. Ferber, Magnetic field induced alignment - orientation conversion Non-linear energv shift and predissociation in Tc2 B 1 state, J. Chem. Phys., 105 p. 37 49 (1996). 

The application of an electric field always causes some physical changes in the medium even if the liquid molecules are non-polar, the electrons in the molecule will be affected by the electric field. The movement of electrons within the molecule results in an induced dipole, ft, and the alignment of the induced dipoles with the electric field gives induced polarization. For example, if a positive charge is placed above the plane of a neutral benzene molecule, the average positions of the electrons will shift upward, giving the benzene molecule a dipole moment whose direction is perpendicular to the molecular plane. In summary, when a non-polar molecule is subjected to an electric field, the electrons in the molecule are displaced from their ordinary positions so that the electron clouds and nuclei are attracted in opposite directions and a dipole is induced thus the molecule temporarily has an induced dipole moment, ft. 

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