Photoionization cross sections for the trans-iron element Se+ from 18 to 31 eV

Absolute photoionization cross-section calculations are presented for Se+ using large-scale close-coupling calculations within the Breit-Pauli and Dirac-Coulomb R-matrix approximations. The results from our theoretical work are compared with recent measurements (Esteves 2010 PhD Thesis publication number AAI3404727, University of Reno, NV, USA; Sterling et al 2011 J. Phys. B: At. Mol. Opt. Phys. 44 025701; Esteves et al 2011 Phys. Rev. A 84 013406) made at the advanced light source (ALS) radiation facility in Berkeley, CA, USA. We report on results for the photon energy range 18.0-31.0 eV, which spans the ionization thresholds of the S-4(3/2)o ground state and the low-lying D-2(5/2,3/2)o and P-2(3/2,1/2)o metastable states. Metastable fractions are inferred from our present work. Resonance energies and quantum defects of the prominent Rydberg resonances series identified in the spectra are compared for the 4p -> nd transitions with the recent ALS experimental measurements made on this complex trans-iron element.