Photoemission and C 1s near-edge absorption from photopolymerized C60 films

Valence band and C 1s X-ray photoemission and near-edge absorption spectroscopy have been used to characterize C60 photopolymerization induced by pulsed laser irradiation of 2.43 eV photons. Photoemission spectroscopy at various photon energies detected the reduced amplitude and broadening of the HOMO and HOMO −1 bands upon polymerization, and the appearance of two additional photoinduced features. In the C 1s NEXAFS, the unoccupied bands of C60 were broadened upon photopolymerization with a small shift (≈0.1 eV) toward higher energy. The dependence of the photopolymerization rate on the incident laser intensity was sublinear for instantaneous laser intensities 70–800 kW/cm2.