EPR Study of NO radicals encased in modified open C60 Fullerenes

Abstract

Abstract. Using pulsed EPR techniques, the low temperature magnetic properties of the NO radical being confined in a C60 derived cage are determined. It is found that the smallest principal g value g3, being assigned to the axis of the radical, deviates strongly from the free electron value. This behavior results from partial compensation of the spin and orbital contributions to the g3 value. The measured value g3 = 0.77(5) yields information about the deviation of the locking potential from axial symmetry. This 17 meV asymmetry is found to be quite small compared to the situation found for the same radical in polycrystalline or amorphous matrices ranging from 300 to 500 meV. The analysis of the temperature dependence of spin relaxation times resulted in a critical temperature of about 3.5 K, assigned to temperature activated motion of the radical with coupled rotational and translational degrees of freedom in the complicated 3-dimensional potential.