CAGE SUBSTITUTION IN METAL-FULLERENE CLUSTERS

Photofragmentation mass spectra of metal-fullerene clusters C60Mx and C70Mx (M={Fe, Co, Ni, Rh}; x=0,...,30) reveal the existence of a react ion channel which yields clusters having the composition C59-2nM and C 69-2nM (n = 0,...,10). Enhanced abundances of clusters with 44, 50, an d 60 atoms, as well as the presence of clusters containing almost excl usively an even number of atoms, indicate that one carbon atom of the fullerene cage is replaced by a transition metal atom. Additional tand em time-of-flight (TOF) experiments on mass selected C59M and C69M ind icate that the initial fragmentation step of this new kind of substitu tionally doped fullerenes is the loss of a neutral MC molecule. Measur ements on preselected C70Rh3 and C70Ir2 were performed in order to mon itor in detail their laser induced transformation into C69Rh and C6Ir. (C) 1998 American Institute of Physics.