Site occupancy and molecular complex formation of 19F ions in fullerenes C60 and C70 studied by TDPAD

TDPAD spectroscopy measurements have been performed on two fullerene samples, C-60 and C-70, with recoil implanted F-19 ions as probe nuclei. Quadrupole coupling frequencies of nu(Q) = 54(1) MHz for C-60 and nu(Q) = 57(1) MHz for C-70 were observed. These frequencies are associated with a C-F molecular complex formation. The C-70 sample was also examined for possible effects due to variation of temperature. No significant changes were observed. An additional frequency of nu(Q) = 13(1) MHz registered for both samples has to be attributed to the formation of H-F complexes. Finally, both samples were analysed for proton dose dependent effects, due to the (p, p'gamma) implantation process but no effects have shown up. Specifically, computational studies based on quantum chemical methods were performed to assist in the interpretation of the experimental results, using the code MOPAC.