EPR investigation of endofullerenes in solution

Samples of Ho rate at C82 and Lu rate at C82 were prepared by arc burning and subsequent HPLC purification. EPR spectra of Lu rate at C82 could be interpreted as arising from unresolved hyperfine interaction with the I=7/2 nuclear spin of 175Lu. At temperatures above 250 K, a thermally activated process, which is tentatively attributed to a hopping process of the encapsulated ion or to time-dependent population of close-lying electronic states, leads to pronounced line broadening. For the Ho rate at C82 sample, no EPR signals could be detected, indicating a high spin state of this molecule. Spin relaxation data of N rate at C60, which was prepared by ion bombardment, could be interpreted by assuming that collision-induced deformation of the carbon shell leads to a fluctuating zero-field splitting, sensed by the quartet spin state of the central encapsulated nitrogen atom. (orig.)