Electrical properties bases permanent moments

Methods for determining permanent dipole moments and polarizabilities can be arbitrarily divided into two groups. The first is based on measuring bulk phase electrical properties of vapors, liquids, or solutions as functions of field strength, temperature, concentration, etc. following methods proposed by Debye and elaborated by Onsager. In the older Debye approach the isotope effects on the dielectric constant and thence the bulk polarization, AP, are plotted vs. reciprocal temperature and the isotope effect on the polarizability and permanent dipole moment recovered from the intercept and slope, respectively, using Equation 12.5. 

Hund s cases are important because they tell the experimentalist what kind of patterns might be found in a spectrum, how to look for these patterns, and what inferences about quantum number assignments can be drawn from the patterns once they are detected. Hund s cases tell the dynamicist how to construct a reduced dimension picture of intramolecular processes. The reduction in dimensionality is based on the existence of approximate constants of motion, eigenvalues of operators that commute with most of the molecular Hamiltonian [see Sections 9.4.9 and 9.4.10]. Hund s cases, embodied in models of vectors precessing about other vectors, explain how information about molecule frame properties (e.g., a permanent magnetic dipole or an electric dipole transition moment) survives rotational averaging and becomes observable in the laboratory frame (and vice versa). 

LC elastomers based on the side-chain and main-chain LC polymers containing rather small concentrations of the chiral mesogens can form SmC mesophase-possessing domains with permanent electric dipole moment, which exhibit piezoelectric properties. The application of an uniaxial mechanical field (shear) produces a centrosymmetric morphology, where the piezoelectric effeas are observed. The piezoelectric coefficient reaches its maximum at a certain shear angle that corresponds to the completion of polydomain to monodomain transformation. The piezoelectric module of different types of such LC elastomers can be higher than those... 

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