Environmental effects on electron spin relaxation in N@ C60

We examine environmental effects of surrounding nuclear spins on the electron spin relaxation of the N@ C60 molecule (which consists of a nitrogen atom at the center of a fullerene cage). Using dilute solutions of N@ C60 in regular and deuterated toluene, we observe and model the effect of translational diffusion of nuclear spins of the solvent molecules on the N@ C60 electron spin relaxation times. We also study spin relaxation in frozen solutions of N@ C60 in C S2, to which small quantities of a glassing agent, S2 Cl2, are added. At low temperatures, spin relaxation is caused by spectral diffusion of surrounding nuclear Cl 35,37 spins in the S2 Cl2, but, nevertheless, at 20 K, T2 as long as 0.23 ms is observed.