Photoabsorption cross section of C60 thin films from the visible to vacuum ultraviolet

Absolute photoabsorption cross sections of C60 thin films are determined in the hν range from 1.3 to 42 eV by using photon attenuation method. The spectrum shows a prominent peak of 1180 Mb at 22.1 eV with several fine structures due to single-electron excitation similarly to the case of C60 in the gas phase. The complex refractive index and complex dielectric function are calculated up to 42 eV through the Kramers–Kronig analyses. From the present data of C60 thin films the cross section curve of a molecular C60 is calculated with an assumption that the polarization effect of surrounding C60 molecules can be expressed by the standard Clausius–Mossotti relation. The spectrum thus obtained shows an excellent agreement with that of C60 in the gas phase measured independently.