Experimental evidence is presented for confinement resonances associated with photoabsorption by a Xe atom in a C60 cage. The giant 4d resonance in photoionization of Xe is predicted to be redistributed into four components due to multipath interference of photoelectron waves reflected by the cage. The measurements were made in the photon energy range 60-150 eV by merging a beam of synchrotron radiation with a mass/charge selected Xe@C₆₀+ ion beam. The phenomenon was observed in the Xe@C(58)(3+) product ion channel. [corrected]

No abstract

Mass-selected beams of atomic Ceq+ ions (q = 2, 3, 4), of C82+ and of endohedral Ce@C82+ ions were employed to study photoionization of free and encaged cerium atoms. The Ce 4d inner-shell contributions to single and double ionization of the endohedral Ce@C82+ fullerene have been extracted from the data and compared with expectations based on theory and the experiments with atomic Ce ions. Dramatic reduction and redistribution of the ionization contributions to 4d photoabsorption is observed. More than half of the Ce 4d oscillator strength appears to be diverted to the additional decay channels opened by the fullerene cage surrounding the Ce atom.

This Letter was published online on 15 November 2010 with a tagging error in the abstract. The last sentence of the abstract should read as ''The phenomenon was observed in the Xe@C 3þ 58 product ion channel.'' The

Abstract. Absolute photoionization cross-section measurements are reported for Se + in the photon energy range 18.0-31.0 eV, which spans the ionization thresholds of the 4 S 3/2 ground state and the low-lying 2 P 3/2,1/2 and 2 D 5/2,3/2 metastable states. The measurements were performed using the Advanced Light Source synchrotron radiation facility. Strong photoexcitation-autoionization resonances due to 4p→nd transitions are seen in the cross-section spectrum and identified with a quantum-defect analysis.PACS numbers: 32.80. Fb, 32.80.Zb, 95.30.Dr, 95.30.Ky, 97.10.Cv, 98.38.Ly