Isotopes buckyballs

Recall that fullerenes include spherical C6o carbon molecules ( buckyballs ) whose cavities can trap other atoms such as helium and argon. (See the accompanying figure.) The scientists postulate that the fullerenes originated in the collapsing gas clouds of stars where the noble gas atoms were trapped as the fullerenes formed. These fullerenes were then somehow incorporated into the object that eventually hit the earth. Based on the isotopic compositions, the geochemists estimate that the im-... 

In its elemental form, carbon can be fonnd as diamond, the hardest naturally occurring substance graphite, an excellent Inbricant or as a fullerene (or buckyball ). Althongh five isotopes are known, only C-12 (98.9 per-centnatural abundance) and C-13 (1.1 percent) are stable. Nevertheless, the presence of trace amounts of C-14, a radioactive isotope (with a half-life of 5,730 years), permits carbon dating of historical objects. 

Isotope ratios of the noble gas atoms inside celestial buckyballs indicate that these ancient carbon cages formed in a stellar environment, not on earth. 

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