Max-Planck-Institut Festkoerperforschung, Stuttgart, 70569, Germany

The coating (with up to 4 layers) was studied of C60 and C70 fullerenes by metal atoms producing C60Mx and C70Mx clusters (M = Li, Na, K, Rb, Cs, Ca, Sr, Ba and x = 0-500). Clusters with complete metal layers proved to be particularly stable and appeared with enhanced intensity in the mass spectra. The no. of atoms required to complete such a layer is identical for each alk. earth metal; the no. of M atoms in the first layer is identical to the no. of carbon rings on the surface of the fullerene coated. A geometrical arrangements with I-symmetry (coated C60) and D5-symmetry (coated C70) are proposed. In coating with alkali metals the stability of the clusters seems to be detd. by the electron configuration; the units C60M6 and C70M6 proved to be exceptionally stable cluster building blocks. An exception to the electronically detd. cluster stability is C60Li12 which was obsd. to be particularly stable. At higher alkali metal coverage of the fullerene an electronic shell structure similar to the pure metal clusters was obsd. in the ionization threshold of the clusters.
 

NATO ASI Ser., Ser. E, 316 215-232, 1996.