title: Relativistic and interchannel coupling effects in photoionization angular distributions by synchrotron spectrocopy of laser cooled atoms.
abstract: We investigate the angular distribution of photoionization fragments at low photon energies (12-40 eV) in an open shell atom, by synchrotron radiation recoil ion momentum spectroscopy in a laser cooled and trapped sample. For cesium atoms, for which relativistic effects play an important role and the ion recoil is relatively small, we could determine large and rapid changes of the asymmetry parameter beta from two, observed for s electrons outside resonances and far from the Cooper minimum. They can be explained by relativistic effects and interchannel coupling arising from final state configuration mixing.
authors.affiliation: Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas (UNICAMP), Box 6165, CEP 13083-970 Campinas-SP, Brazil.
authors.forename: L H
authors.initials: LH
authors.lastname: Coutinho
authors.forename: R L
authors.initials: RL
authors.lastname: Cavasso-Filho
authors.forename: T C R
authors.initials: TC
authors.lastname: Rocha
authors.forename: M G P
authors.initials: MG
authors.lastname: Homem
authors.forename: D S L
authors.initials: DS
authors.lastname: Figueira
authors.forename: P T
authors.initials: PT
authors.lastname: Fonseca
authors.forename: F C
authors.initials: FC
authors.lastname: Cruz
authors.forename: A
authors.initials: A
authors.lastname: Naves de Brito