An investigation of photoassisted diffusion of oxygen in solid C₆₀ films using resonant alpha-scattering

The interaction of molecular oxygen with thin C₆₀ films was investigated using the 3.04 MeV resonance in the ¹⁶O(α, α)¹⁶O elastic scattering reaction to measure the concentration profile of oxygen in the fullerene films. A thin (d ≍ 20 nm) layer containing oxygen was observed on the surface of C₆₀ films (d ≍ 200 nm) exposed to ∼1 atm of O₂ for 1 h in the absence of light. In contrast, oxygen was uniformly distributed throughout the entire film when samples were irradiated for 1 h with either a 488 nm Ar ion laser or Xe lamp in the presence of ∼1 atm of O₂. This O₂ uptake was found to be both power dependent and reversible.