Potential barrier effects on double excitation series of Ca I and Sr I

Abstract

Abstract Observations of the series due to simultaneous excitation of two valence electrons to 4p ns,nd in Ca i and 5p ns,nd in Sr I are reported. The importance of the angular momentum barrier for the doubly excited nd series and, by comparison, for the nd series of singly excited even parity states is inferred with the help of single configuration Hartree-Fock calculations. This contrasts with the situation in Mg Ι, where wavefunction collapse does not occur in the doubly excited 3p nd series.