Effects of Lattice Vibrations on Angular Correlations

Abstract

A theory of the influence of the environment on ?-? angular correlation is presented. The theory is formulated by using the damping theory, and the perturbation factor of the perturbed angular-correlation function, which contains the effects of the changes of the states of the environment on the angular correlation, is obtained. In the solid environment, the effects of the lattice vibrations on the electric quadrupole coupling have been analyzed by using the normal-mode expansion of the lattice displacements; and the perturbed angular correlation function is shown to be a function of the crystal temperature. In order to determine the nuclear electric quadrupole moment in an excited state, which cannot be done by the usual microwave methods, a rotational technique is suggested and the theory has been developed for the case of asymmetric fields. For the special case of an axially symmetric crystalline field, the present theory predicts a phase shift in the rotational pattern of anisotropy.