Fourier transform EPR study of N@C60 in solution

Using pulsed EPR techniques, the electron spin relaxation properties of nitrogen atoms encapsulated in C60 have been studied. Because of the high symmetry of the cage, most of the conventional relaxation mechanisms otherwise affecting electron spins in solution are absent, resulting in an exceptional homogeneous ERP linewidth of only 2.5 kHz. Apparently, solvent collision-induced deformations of the carbon shell which modulate the zero-field-splitting sensed by the quartet spin state of N@C60 are the dominant spin relaxation mechanism.