Regular Article

Coupled channel effects on resonance states of positronic alkali atom^★

Department of Chemistry, Tohoku University, Sendai 980-8578, Japan

^a e-mail: t.ymst@dc.tohoku.ac.jp

Received: 21 August 2017
Received in final form: 13 November 2017
Published online: 18 January 2018

Abstract

S-wave Feshbach resonance states belonging to dipole series in positronic alkali atoms (e⁺Li, e⁺Na, e⁺K, e⁺Rb and e⁺Cs) are studied by coupled-channel calculations within a three-body model. Resonance energies and widths below a dissociation threshold of alkali-ion and positronium are calculated with a complex scaling method. Extended model potentials that provide positronic pseudo-alkali-atoms are introduced to investigate the relationship between the resonance states and dissociation thresholds based on a three-body dynamics. Resonances of the dipole series below a dissociation threshold of alkali-atom and positron would have some associations with atomic energy levels that results in longer resonance lifetimes than the prediction of the analytical law derived from the ion–dipole interaction.