Photoabsorption cross section of the isolated Ce@C82 at the 4d → εf resonance of Ce


K.Mitsuke1,2), J.Kou1), T.Mori1), Y.Haruyama3), Y.Kubozono3)

1)Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
2)Graduate University for Advanced Studies, Myodaiji, Okazaki 444-8585, Japan
3)Department of Chemistry, Okayama University, Okayama 700-8530, Japan

The yield curves for photoions from Ce@C82 are measured by using synchrotron radiation in the photon energy range from 90 to 160 eV. Parent Ce@C82z+ and fragment ions C60z+ and C70z+ are observed in a mass spectrum (z = 1 and 2). The yield curves for principal ionic species exhibit broad resonance in the region hν =120 - 140 eV which is ascribed to the 4d → εf giant dipole resonance of the encapsulated Ce atom. The total photoabsotpion cross section of Ce@C82 was determined from photofragmentation cross sections for respective ions to be 36 and 46 Mb at hν = 110 and 130 eV, respectively. Evaluation of the cross section was made from the count rate of the ion signal, photon flux of synchrotron radiation, number density of Ce@C82 in the ionization region, ionization volume, detection efficiency of our mass spectrometer, repetition rate of the pulsed electric field applied to the ionization region, and average residence time of the ions in the probed region where the pulsed voltage can guide them to the electron multiplier detector.