Endohedral Rare-Gas Radiofullerenes by Nuclear Recoil

Abstract

In this section, we review research that shows strong evidence for rare-gas endohedral radiofullerene formation as a result of nuclear recoil that follows nuclear reactions. Pioneering neutron activation studies by Braun and Rausch, are described [1]. The subsequent discovery of stable rare gas interstitial fullerenes by Gadd et al. [19–21, 25], has enabled the gamma produced recoil mechanism of Braun and Rausch to be studied in greater detail [13, 14]. The preparation and thermal behaviour of rare gas interstitial fullerenes is briefly described as well as their behaviour to neutron irradiation. The results show the authenticity of Braun and Rausch’s earlier experimental work and an observed isotope effect indicates the unique nature of the endohedral formation process. Further neutron activation studies [15] of the rare gas interstitial Xe/C₆₀, combined with the use of gamma spectroscopy and high pressure liquid chromatography (HPLC) shows strong evidence for an eluted fraction containing the radioactive endohedral fullerene, Xe@C₆₀. The research of Ohtsuki et al. [10] is described, who have independently been studying an alternative nuclear activation process for producing rare gas radionuclides in the presence of fullerenes. Using HPLC, they have also found direct evidence for endohedral formation as a result of nuclear recoil. Important factors relating to the nuclear recoil mechanism of endohedral rare gas radiofullerene formation are discussed as well as the elegant state of the art ab initio molecular dynamics simulations by Ohtsuki et al. [10].