Screening Constant per Unit Nuclear Charge Studies of Rydberg Resonances Due to the 4p → nd and ns Transitions in Se+ Ions

Abstract

Calculations of high-lying energy resonances of 12 Rydberg series due to the 4p → nd and 4p → ns transitions from the 4s24p3 3S°3/2 ground-state and the 4s24p3 2P°3/2,1/2 and 4s24p3 2D°5/2,3/2 metastable states of the Se+ ion are reported. The calculations believed to be the first theoretical ones are performed using the Screening Constant per Unit Nuclear Charge (SCUNC) method up to n = 40. Analysis of the present results is achieved in the framework of the standard quantum-defect theory and of the SCUNC-procedure by calculating the effective nuclear charge. For many resonances, the SCUNC-method reproduces the ALS measurements excellently [Esteves et al., Phys. Rev. A, 84 013406 (2011)] up to n = 25. However, for some resonances belonging to the 4s24p2 (1D2)nd (2D) and 4s24p2 (1D2)ns (2D) and to the 4s24p2 (1D2)nd (2S) and 4s24p2 (1D2)nd (2P1/2) Rydberg series, the ALS data overlap at high n values. In addition, negative quantum-defect values were determined where positive values are allowable. In the present work, positive quantum defect values almost constants are obtained along all the series investigated up to n = 40, and the narrow resonances are clearly separated. Overall, the present theoretical study provides confidence in the ALS data on Se+ ions for astrophysical interest as far as the understanding of the chemical evolution of Se in the universe is concerned.