A study of 100 keV Co+-implanted C-60 films with Rutherford Backscattering and Raman spectroscopy has revealed the pronounced cobalt translation from the surface layer of amorphous carbon into the deeper crystalline fullerene due to post-implantation annealing at 300 degrees C. Carbon density gradient along the film depth is discussed as a driving force of this effect. Cobalt deficit in the doped fullerene layer, detected by means of ion beam analysis, suggests ionization of the C60 molecules under the collisions with 2 MeV He+ ions. (c) 2006 Elsevier B.V. All rights reserved.