GENERATION AND HYDROGENATION OF ADJACENT-PENTAGON FULLERENES - ASTROCHEMICAL CONSIDERATIONS

Recent theories advanced to account for diffuse interstellar (IS) bands and for several other IS spectral features have included as postulated carriers of these features the fullerene molecule C60 and its hydrogenated analogues. We propose that the most likely sites of hydrogenation upon a fullerene under IS conditions are at adjacent 'defects' which are present upon the carbon surfaces of some fullerenes. C-H and C-C bonds associated with such sites are expected to exhibit substantially different spectral characteristics to those bonds at other sites. Hydrogenation of these adjacent-pentagon 'defect' sites also provides a plausible mechanism for the stabilization of fullerenes smaller than C60, which might reasonably be expected to accompany the circumstellar generation of larger fullerenes.