4d→4f dipole resonance of the metal atom encapsulated in a fullerene cage: Ce@C ₈₂

The yield curves for photoions from Ce@C ₈₂ are measured by using synchrotron radiation in the photon energy range from 90 to 160 eV. Parent Ce@C ₈₂ ^z+ and fragment ions C ₆₀ ^z+ and C ₇₀ ^z+ are observed in a mass spectrum (z=1 and 2). The yield curves for doubly charged ionic species exhibit broad resonance in the photon energy region of from 120 to 140 eV which is ascribed to the 4d→4f giant dipole resonance of the encapsulated Ce atom. The total photoabsorption cross section of Ce@C ₈₂ was determined from partial photoionization cross sections for formation of the parent and fragment ions to be 5.3 _-1.1 ^+1.8 and 19.6 _-3.9 ^+6.5 Mb at photon energies of 110 and 130 eV, respectively.