Analysis of ⁸⁷ Rb and ¹³ C Hyperfine Interaction in Rb ₃ C ₆₀

We report on 87Rb NMR measurements on rubidium-doped Buckminster fullerene C60. We found direct correlation between the the temperature-dependent shift of 87Rb and 13C NMR lines in Rb3C60. By relating the temperature-dependent shifts to the independently determined temperature-dependent susceptibility, we were able to derive the isotropic hyperfine interaction for both 13C (a = 2π·2.0 MHz) and the different Rb sites, namely a = -2π·26 MHz for the octahedral site, a = -2π·30 MHz for the tetrahedral site of Rb3C60 and a = -2π·16 MHz for the so called T' site. In addition, we have determined the 13C hyperfine tensor with principal values 2π·(9.2, -3.9, -5.3) MHz.