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

Abstract

TDPAD spectroscopy measurements have been performed on two fullerene samples, C₆₀ and C₇₀, with recoil implanted ¹⁹F ions as probe nuclei. Quadrupole coupling frequencies of ν_Q= 54(1) MHz for C₆₀ and ν_Q= 57(1) MHz for C₇₀ were observed. These frequencies are associated with a C–F molecular complex formation. The C₇₀ sample was also examined for possible effects due to variation of temperature. No significant changes were observed. An additional frequency of ν_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'γ) 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.