Photoemission spectral analysis of fullerene films polymerized by argon plasma treatment

Photoemission spectral analysis was carried out on plasma polymerized fullerene (C60) films prepared by sublimating C60 under an argon plasma. In the photoemission analysis, the overall distribution of the shallow valence band states of the plasma-treated C60 was compared with pristine C60. These changes suggest that the pi conjugation of the shallow valence band states of two C60 molecules is induced by polymerization during the plasma treatment. To investigate the changes in the onset of the shallow valence band states brought about by polymerization, the orbital energy levels in C60 dimers were examined using the semiempirical AM-1 method. Calculations showed that the highest occupied molecular orbital levels of the dimers were shallower than that of C60. (C) 2003 American Institute of Physics.