Interaction of U³⁺ Pairs in $LaCl3$

We report the first measurement of actinide pairs in the well studied $LaCl3$ system. Second shell U³⁺ pairs were observed by EPR, resulting in the determination of the anisotropic interaction tensor for 3rd and 6th nearest neighbors. As this yields a precise measure of the superexchange contribution, the results are discussed in terms of superexchange paths available to the pair in question. Comparison is made of these results to those of second shell Nd³⁺ pairs in $LaCl3$⁠.