Change of 7Be decay rate in exohedral and endohedral C60 fullerene compounds and its implications

The half-life of exohedral Be-7-C-60 complex and that of Be-7 implanted in a gold foil have been found to be about the same within approximate to 0.2%. Using a radiochemical technique, we also measured that the probability of formation of endohedral Be-7@C-60 complex by nuclear implantation technique was (5.6 +/- 0.45)%. We also find that the half-life of endohedral Be-7@C-60 complex is shorter than that of exohedral complex by more than 1%. An analysis of these results using linear muffin-tin orbital method calculations indicates that most of the implanted Be-7 ions in fullerene C-60 stay at a distance of approximate to 5.3 A from the centers of nearest C-60 molecules forming exohedral compounds and those who enter the fullerene cages go to the centers of the cages forming endohedral Be-7@C-60 compounds.