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Using Raman scattering we have observed a phototransformation of C60 films on Si(100) from a face-centered-cubic (fcc) phase to a second solid phase leaving the C60 molecules intact. Furthermore, photoassisted oxygen diffusion into the deep bulk is detected using alpha resonance scattering. The Raman spectrum for oxygen-doped C60 is found to be similar to the result for oxygen-free fcc C60, and oxygen is found to harden the film against phototransformation.

Using variable-angle ellipsometry and normal incidence reflection/transmission optical techniques we have measured the dielectric function ε(ω) at room temperature for solid C70 films over the photon energy range 0.5≤E≤5.3 eV. The onset of absorption across the highest-occupied-molecular-orbit (HOMO)–lowest-unoccupied-molecular-orbit (LUMO) gap is measured to be 1.25 eV. Furthermore, structure in the interband absorption at 2.41, 3.10, 3.50, and 4.45 eV is observed. The refractive index at zero frequency is estimated to be n(0)=1.94 as compared to the value n(0)=1.90, which we obtained for solid C60 from our previous study.