Photoionization of tungsten ions: experiment and theory for W5+

Abstract

Abstract Experimental and theoretical cross sections are reported for single-photon single ionization of W5+ ions. Absolute measurements were conducted employing the photon–ion merged-beams technique. Detailed photon-energy scans were performed at (67 ± 10) meV resolution in the 20–160 eV range. In contrast to photoionization of tungsten ions in lower charge states, the cross section is dominated by narrow, densely-spaced resonances. Theoretical results were obtained from a Dirac–Coulomb R-matrix approach employing a basis set of 457 levels providing cross sections for photoionization of W5+ ions in the 4 f 14 5 s 2 5 p 6 5 d 2 D 3 / 2 ground level as well as the 4 f 14 5 s 2 5 p 6 5 d 2 D 5 / 2 and 4 f 14 5 s 2 5 p 6 6 s 2 S 1 / 2 metastable excited levels. Considering the complexity of the electronic structure of tungsten ions in low charge states, the agreement between theory and experiment is satisfactory.