Studies of ionised atoms with collision-based spectroscopy and laser spectroscopy

Abstract: Atomic structure and collision properties of ionised atoms have been studied usingcollision-based spectroscopy and fast ion beam-laser spectroscopy.Collision induced photon emission spectra of Xe VI, Xe VII and Xe VIII andthe potassium like metal ions Mn VII, Fe VIII and Co IX have been recorded with a beam of multiply charged ions from an ECR (electron cyclotron resonance) ion source passing through an atomic target. Previously unknown spectral lines have been identified and thereby new energy levels established. In particular, transitions between highly excited states of multiply charged xenon ions have been observed and ionisation limits, quantum defects and core polarisabilities obtained.Single- and double-electron capture in slow C4+ on Ne collisions have been investigated by combining photon emission and translational energy-gain data. The information in the photon emission spectra made it possible to distinguish processes that gave similar energy-gain data. A substantial configuration selectivity has been observed for the so-called one-step mechanism for double electron capture. Mechanisms for populating doubly excited Ar7+ states with helium as a target have also been studied. The results indicated that the main process of populating doubly excited states of the electron configuration 2p53p2 in sodium like Ar7+ is a one electron capture to 2p53snl in metastable Ar8+ states.Very high resolution studies of hyperfine structure and isotope shifts of Eu II and Sm II have been studied using fast ion beam-laser spectroscopy. Magnetic dipole and electric quadrupole coupling constants have been derived.