Photoionization of Rb²⁺ions in the valence energy region 37–44 eV

Abstract

Absolute photoionization cross sections for the Rb 2+ ion were recently measured at high resolution over the energy range 37.31 eV -44.08 eV, with autoionizing Rydberg resonance series identified, using the photon-ion merged-beam setup at the Advanced Light Source (als) in Berkeley (Macaluso D A et. al. J. Phys. B: At. Mol. Opt. Phys. 49 (2016) 235002; 50 (2017) 119501). Detailed photon-energy scans taken at 13.5 ± 2.5 meV bandwidth illustrated multiple Rydberg resonance series associated with the ground and metastable states. Here we present theoretical cross section results obtained using the Dirac-Coulomb R-matrix approximation with a detailed analysis of the resonances. The calculations were performed for the 3d 10 4s 2 4p 5 2 P o J , J = 3 2 ground state and the corresponding 3d 10 4s 2 4p 5 2 P o J , J = 1 2 metastable level. Results from the large-scale calculations are benchmarked against the als high-resolution measurements and reproduce the dominant resonance features in the spectra, providing confidence in the theoretical work for astrophysical applications.

Screening Constant by Unit Nuclear Charge Photoionization of Rb\(^{2+}\) Ions

“…f 1 ( 3 P 1 )= .797 ± 0.071; µ = 13. The present SCUNC calculations are compared to the DARC calculations (McLaughlin and Babb [17]) and the ALS measurements (Macaluso et al [18,19] [17]) and the ALS measurements (Macaluso et al [18,19] [17]) and the ALS measurements (Macaluso et al [18,19] [17]) and the ALS measurements (Macaluso et al [18,19] [17]) and the ALS measurements (Macaluso et al [18,19]…”

“…In tandem with the measurements, Breit-Pauli R-matrix calculations were performed in the intermediate coupling jK to facilitate the identification of several highly excited Auger Rydberg resonance states of the Rb 2+ ions. Very recently, McLaughlin and Babb [17] used a fully relativistic approach within the Dirac-Coulomb R-matrix (DARC) approximation to calculate the cross sections for ground and metastable states. Although very good agreement are found between the DARC [17] and ALS measurements [19], calculations can be improved as maximum energy differences between theory and experiment at 0.008 eV are observed for the 4s 2 4p 4 ( 1 D 2 )nd and 4s 2 4p 4 ( 3 P 1 )nd Rydberg series.…”

“…Very recently, McLaughlin and Babb [17] used a fully relativistic approach within the Dirac-Coulomb R-matrix (DARC) approximation to calculate the cross sections for ground and metastable states. Although very good agreement are found between the DARC [17] and ALS measurements [19], calculations can be improved as maximum energy differences between theory and experiment at 0.008 eV are observed for the 4s 2 4p 4 ( 1 D 2 )nd and 4s 2 4p 4 ( 3 P 1 )nd Rydberg series. The motivation of this work is to use the Screening constant by unit nuclear charge (SCUNC) formalism (Sakho [20][21][22]; Ba et al [23];…”

“…. Comparisons are done with the Advanced Light Source (ALS) measurements of Macaluso et al[18,19] and with the fully relativistic approach within the Dirac-Coulomb R-matrix (DARC) calculations of McLaughlin and Babb[17]. Analysis of the values of the nuclear effective charge Z * listed in the first entry of each table indicate that Z * max > Z core = 3.0.…”

“…This allows one to expect the high lying data up to n = 40 to be useful benchmark data for astrophysical applications. In the work of McLaughlin and Babb[17], fully relativistic approach within the Dirac-Coulomb R-matrix calculations were performed in the intermediate coupling jK Breit-Pauli approximation from the DARC 687 level calculations. In the present work, very precise photoionization data are obtained within the very simple formalism of the SUCNC method.…”