The intercalation of Ar into C-60 films

In this Communication we discuss how unimplanted and implanted films (Y and Au implanted) of C-60, when hot isostatically pressed (HIPed) at a pressure of 170 MPa (1.7 kbar) of Ar and temperatures of 300 or 400 degrees C, show substantial uptake of Ar into the film. Rutherford backscattering (RBS) provides an effective method for elucidating film composition, showing the films to have similar to 1.5 at. % of Ar, consistent with a stoichiometry close to Ar-1 C-60. The Ar was found to diffuse from the films when these were held in a vacuum at 300 degrees C. It could subsequently be reincorporated into the film by re-HIPing, with uptake of a similar amount of Ar. LR spectroscopy showed that the C-60 IR absorptions remain unchanged throughout uptake of the Ar and its subsequent loss during heating at 300 degrees C. It appears that the Ar is trapped interstitially in the films outside the C-60 cages.