On the action of UV photons on hydrogenated fulleranes C₆₀H₃₆and C₆₀D₃₆

Fulleranes, the hydrogenated fullerenes C 60 H 36 and C 60 D 36 have been synthesized in n-hexane where they show an absorption maximum at 217 nm in their electronic absorption spectra with molar extinction coefficients 217 = 17 140 and 16 480 L cm -1 mol -1 , respectively, which correspond to absorption cross-sections of order 6500 Mbarn, about 10 times higher than for C 60 . We find that the absorption curves measured for these two fulleranes fit well the wavelength, width and shape of the ultraviolet (UV) bump (217 nm) in the extinction curve of the diffuse interstellar medium. If present in the interstellar medium these fulleranes would contribute significantly to the bump extinction, although interstellar carbon budget considerations indicate that C 60 H 36 cannot be the only contributor.