SPIN-LATTICE RELAXATION IN TRIPLET-EXCITE D STATES OF ORGANIC MOLECULAR-CRYSTALS - THE IMPURITY CLUSTERS

Theoretical investigations of the EPR line shape and spin-lattice rela xation processes in the triplet-excited impurity clusters of organic m olecular crystals (naphthalene) are carried out, The ABA (BAB)-cluster s are considered. It is found that sharp acceleration of spin-lattice relaxation rate and EPR line broadening take place in the area of spin underlevels crossing. It is shown that this effect may be observed at different EPR frequencies in the case of AB-, AA- and ABA-clusters.