Intercalation in C/sub 60/: High resolution /sub13/C NMR results

Summary form only given. We present High Resolution /sup 13/C NMR (HRNMR) studies performed on C/sub 60/ intercalated with 0/sub 2/, K or Rb. For C/sub 60/ molecules surrounded by n paramagnetic oxygens (0 /spl les/ n /spl les/ 2), it is now well known that the isotropic part of the resonance is shifted downfield by n x 0.7 ppm from the pure C/sub 60/ resonance at 143.6 ppm. The extent of anisotropy /spl Delta/ of the resonance of C/sub60/ molecules surrounded by only one oxygen in one of the six neighbouring octahedral sites is of the order of 70 ppm. /spl Delta/ depends on the distance between the oxygen and the surface of the C/sub 60/ molecule and, as such, presents a slight variation at the first order transition temperature (260 K). This shows that the oxygen intercalation does not significantly modify the thermodynamic properties of the system. In the case of K and Rb intercalation, HRNMR allows us to define accurately the isotropic resonances corresponding to the various thermodynamically stable phases. On the basis of the analysis of the observed NMR spectra, we discuss the effects of the intercalation on the molecular dynamics and on the electronic properties of these compounds.