Evidence for Rare Gas Endohedral Fullerene Formation from γ Recoil from HPLC Studies

Abstract

In this paper, we present the first direct evidence for the formation of endohedral fullerenes from prompt γ emission of neutron irradiated Xe held interstitially in the C 60 lattice. Following neutron activation, solutions of the irradiated solid were analyzed by high-pressure liquid chromatography and γ spectroscopy which showed Xe radioisotopes to be present in fractions that eluted at longer times relative to untreated C 60 . The observation of Xe radioisotopes at these particular times was attributed to elution of compounds based on Xe@C 60 . Additional support for this conclusion was obtained from isotopic ratios measured by γ spectroscopy. The present results provide convincing evidence in support of the γ recoil mechanism for trapping radionuclides in fullerene cages which had previously been inferred from indirect evidence.