SEARCH FOR FULLERENES AND PAHS IN THE DIFFUSE INTERSTELLAR-MEDIUM

Recent studies suggest carbon-containing molecules as the best candida tes for carriers of the unidentified diffuse interstellar bands (DIBs) , considering their abundance and ability to form stable bonds in inte rstellar space. We have searched for new DIBs in the near-IR and have detected two new diffuse bands that are consistent with laboratory mea surements of C-60(+) in a neon matrix. Criteria for this possible iden tification are discussed. From these observations and the DIB measured absorption, we estimate that up to 0.9% of interstellar carbon could be in the form of C-60(+). We also searched for polycyclic aromatic hy drocarbon (PAH) cations and have derived corresponding limits for the presence of the coronene C24H12 and ovalene C32H14 cations in space. W e have studied the ionization properties of these PAH cations, which c ould explain their selective destruction. From these results we discus s the role of fullerenes and PAHs as possible DIB carriers.