C-13 MAS NMR INVESTIGATIONS OF ALKALI DOPED C-60

Results of C-13 MAS NMR measurements of the RbxC60 system (x = 2.75, 3 , 4, 6) and the A(6)C(60) compounds (A = K, Rb, Cs) are presented. Spe cial attention was paid to sample preparation in order to suppress eff ects of impurities and lattice defects due to imperfect C-60 starting material. The C-13 MAS NMR measurements of the Rb,C,, system demonstra te the usefulness of this method to reveal valuable information about its phase diagram. The existence of underdoped R(4)C(60) is proved. We ll resolved lines in all investigated A(6)C(60) compounds confirm the orientational order of the C-60 ions. An assignment of the signals to the three magnetically inequivalent carbon atom positions in the cryst al structure is proposed.