Effect of Slow Rotational Diffusion on Angular Correlations

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Abstract
The theory for perturbed angular correlations of gamma radiation has been extended to include the possibility of adiabatic variation in the interaction Hamiltonian, K, for the intermediate state. The calculation begins from a polycrystalline model; it is then shown that adiabatic variation in K introduces a time dependence into the angles which express the orientation of the molecular frame. If this variation arises from slow rotational diffusion of the principal axis of K, then each term of the polycrystalline correlation is simply modified to include the factor, exp[−k(k+1)Dt], where D is the rotational diffusion constant for molecular reorientation in the intermediate state. The relevance of the adiabatic limit to the use of perturbed angular correlations of gamma radiation for study of the motion of radioactive species in viscous media is discussed.