Photo-induced processes of endohedral fullerene ions: Experiment

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The response of atoms A encapsulated within spheres of carbon atoms to single-photon absorption will be studied. Pure (with respect to mass and charge) beams of endohedral fullerene ions in different charge states will be exposed to synchrotron radiation with energies 17 to 340 eV at the Advanced Light Source (ALS) in Berkeley and with energies of 250 to 3000 eV at PETRA III in Hamburg. Within this wide energy range, different subshells of the encapsulated atom can be excited or ionized. Photoelectron production and subsequent decay of the atom result in illumination of the fullerene sphere from within by electrons or photons of greatly different but always well quantified energies. The emission of electrons and photons from the central atom is influenced by the surrounding sphere which gives rise to a large variety of phenomena of ionization and fragmentation of the whole endohedral fullerene complex with additional modifications of the cross sections by interference effects. Quantitative experimental studies of these phenomena are badly needed for testing and guiding the world-wide theoretical efforts to correctly model the behavior of endohedral fullerenes exposed to electromagnetic radiation. Variation of the initial ion charge state will provide new insights into the electro-chemistry of encapsulated atoms. By using very heavy encapsulated atoms it is planned to demonstrate the effect of heavy x-ray absorbers on surrounding material which is of interest for efficiently damaging cancer cells by electromagnetic radiation. The experimental effort will be coordinated with the theoretical work carried out at the Frankfurt Institute for Advanced Studies.