IR and Raman investigations have been carried out on purified LiΓ60 and LiΓ70 produced by low-energy ion implantation. The structural interpretations, based on theoretical considerations and comparison of the obtained vibrational spectra with those of different known fullerene oligomers, have shown that neither of the chromatographically isolated endohedral species (LiΓ60(70)) correspond to monomeric nonderivatized molecules. We ascribe the two different fractions of LiΓ60 to a double-bonded dimer and a trimer, presumably with the shape of closed triangle. The infrared and Raman spectra of the LiΓ70 compound are similar to those of (C70)2, and we therefore propose for this species the structure of a double-bonded dimer (LiΓ70)2. The IR spectra of the LiΓ60 fractions prepared with 6Li and 7Li isotopes are identical except for the position of broad bands at about 450-600 cm-1, originating from vibrational-rotational movement of the Li+ cation inside the carbon cage.
|Number of pages||12|
|Journal||Journal of Physical Chemistry B|
|State||Published - 16 Oct 2003|