¹³C-NMR in Iodine and Potassium Intercalated C₆₀ Solid

抄録

Iodine intercalated C₆₀, I_2.29C₆₀, was studied by ¹³C NMR above 160 K. A sharp NMR signal and a strong temperature-dependent spin-lattice relaxation time, T₁, indicated a presence of C₆₀ molecular rotation much higher than 10 kHz at least down to 160 K. No evidence of metallic characteristics was found in the NMR shift (143±1 ppm) and the T₁ (40±5 sec at room temperature). In K₃C₆₀, metallic behavior, T₁T∼constant, was observed at the carbon sites between 20 K and 100 K. Electronic density of states at the Fermi level, N(E_F), in I_2.29C₆₀ was estimated to be smaller than 0.12 of that in K₃C₆₀, assuming a relationship between N(E_F) and T₁T for normal metals.