Deuteron quadrupole coupling in benzene: librational corrections using a temperature-dependent Einstein model, and summary. The symmetries of electric field gradients and conditions for η = 1

Abstract

Librational corrections are added to previous single-crystal and polycrystalline measurements of the deuteron quadrupole coupling constant in benzene. The results are related to gas-phase and liquid-crystal measurements and to theoretical values. A ‘temperature-dependent Einstein model’ is introduced for the purpose. The group-theoretical relations of the electric field-gradient (EFG) tensor to the nuclear site symmetry are discussed. The conditions for η = 1 for reorientational processes are identified.