Abstract

  The recent confirmation of the presence of interstellar fullerenes and of the first identification of two strong diffuse interstellar bands (DIBs) attributed to C60+ justify trying to reassess the overall importance of interstellar fullerene compounds and the chance they could be carriers of more DIBs. I will first recall the general properties of fullerenes in interstellar conditions as regards structure, ionization, visible and IR spectra, chemistry, formation/destruction and abundances. I will then review more specifically the various classes of possible interstellar fullerenes: pure fullerenes of various sizes; association of a metal atom inside (or outside) the carbon cage; inclusion of hetero-atoms (Si, N…) in the carbon network of the cage; hydrogenated fullerenes (fulleranes); and association of fullerenes with PAHs.

  The first identification of a DIB carrier as C60+ strengthens the proposition that fullerenes could be major DIB carriers. Nevertheless, it seems unlikely that most fullerene compounds might be carriers of strong DIBs, with the exception of a few abundant ions, such as C60+, and perhaps other pure fullerene cations, a few metallo- or hetero-fullerenes (neutral and cations) and some fulleranes in special conditions. On the other hand, it seems probable that various fullerene compounds might account for a number of weak DIBs. The lack of precise information about the very complex optical spectra and interstellar abundances still precludes defined assessment of the importance of fullerenes as DIB carriers. However, the detection of C60+ confirms that fullerenes are key candidates, although it seems unlikely that they are the only important DIB carriers. Anyway, DIBs appear as the most promising way of tracing the interstellar abundances of a number of fullerene compounds.