Study of Plasmon Resonances in Single Photoionization of Carbon Fullerene Molecular Ions
AuthorThomas, Christopher Michael
AdvisorPhaneuf, Ronald A
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Beams of carbon fullerene ions containing 40 to 84 carbon atoms were irradiated by monochromatized synchrotron radiation at photon energies ranging from 18-70 eV at 0.5 eV intervals. Single photoionization was studied over this energy range using a merged-beams research endstation at the Advanced Light Source and absolute photoionization cross sections were measured. Electric-dipole-excited surface and volume plasmon resonances due to collective excitations of valence electrons were characterized and quantified by Lorentzian fits. Resonance parameters such as lifetimes and oscillator strengths were calculated and compared. Results for the photoionization of C60+ were compared to previously reported measurements. At higher photon energies, single photoionization accompanied by fragmentation of carbon pairs becomes relatively more important compared to pure single ionization and needs to be considered.