SIMULATED ROTATIONAL BAND CONTOURS OF C-60 AND THEIR COMPARISON WITH SOME OF THE DIFFUSE INTERSTELLAR BANDS

Rotational band contours of some predicted electronic spectra of the i cosahedral molecule C60 have been calculated. Reasonable molecular con stants have been obtained from the experimentally measured geometry of the molecule in the ground electronic state and some assumed geometri es for the excited state. The contours are calculated at a range of te mperatures corresponding to those which might be expected in the inter stellar medium under various conditions. The simulated contours are co mpared to the observed spectra of the unassigned diffuse interstellar bands, which are seen in the absorption spectra of various stars. We c onclude that, for rotational temperatures above 100 K, the simulated p rofiles can reproduce the form and peak width of some of the interstel lar absorption bands, but note that the published low resolution ultra violet and visible spectra Of C60 do not reveal peaks corresponding to any of the major diffuse interstellar bands (DIBs). Our simulations c an also be extended to a more general C60 Species and we suggest that until more laboratory spectra of the parent molecule and its ions are obtained, polyhedral carbon species cannot be ruled out as carriers of some of the DIBs.