Enhanced thermal stability and spin-lattice relaxation rate of N@C60   inside carbon nanotubes
  We studied the temperature stability of the endohedral fullerene molecule, N@C60, inside single-wall carbon nanotubes using electron spin resonance spectroscopy. We found that the nitrogen escapes at higher temperatures in the encapsulated material as compared to its pristine, crystalline form. The temperature dependent spin-lattice relaxation time, T_1, of the encapsulated molecule is significantly shorter than that of the crystalline material, which is explained by the interaction of the nitrogen spin with the conduction electrons of the nanotubes. 
S. Toth, D. Quintavalle, B. Nafradi, L. Korecz, L. Forro, and F. Simon