Formation of various types of metallofullerenes by laser ablation of externally doped fullerenes C60Mx (M=Sm, Pt, Ni, La, Y, and Rh)

Abstract

A photofragmentation study of metal fullerides C60Mx (M=Sm, Pt, Ni, La, Y, and Rh) by excimer laser ablation-TOF mass spectrometry shows that many kinds of metallofullerenes have been observed in both the positive and negative ionic modes. For C60Mx (M=Sm, Pt, and Ni), the metal atom is incorporated into the network of the fullerene cage to replace one carbon atom of the cage forming substitutional metallofullerene. While in the case of metal fullerides C60Mx (M=La, Y), evidence of the encapsulation of La and Y atoms in fullerene cages forming endohedral fullerenes has been observed. Different from the above two cases, the laser ablation of rhodium fulleride C60Rhx(x≈1) produces two sequences of rhodium-containing fullerene clusters C2nRh and C2n+1Rh(2n=50–62). Odd-numbered all-carbon clusters in the fullerene regime are observed in our laser ablation study of all the metal fullerides in the negative ion channel. The structures of metallofullerenes C2n+1M and C2nM with an even and odd number of total atoms, respectively, are discussed. Formation mechanisms with the participation of odd-numbered all-carbon fullerene clusters as intermediates are supposed.