Experimental and theoretical results are reported for photoionization of
Ta-like (W+) tungsten ions. Absolute cross sections were measured in the
energy range 16 to 245 eV employing the photon-ion merged-beam setup at the
Advanced Light Source in Berkeley. Detailed photon-energy scans at 100 meV
bandwidth were performed in the 16 to 108 eV range. In addition, the cross
section was scanned at 50 meV resolution in regions where fine resonance
structures could be observed. Theoretical results were obtained from a
Dirac-Coulomb R-matrix approach. Photoionization cross section calculations
were performed for singly ionized atomic tungsten ions in their 5s25p65d4(5D)6s6DJ, J=1/2, ground level and the associated
excited metastable levels with J=3/2, 5/2, 7/2 and 9/2. Since the ion beams
used in the experiments must be expected to contain long-lived excited states
also from excited configurations, additional cross-section calculations were
performed for the second-lowest term, 5d^5 \; ^6{\rm S}_{J}, J=5/2, and for
the 4F term, 5d^3 6s^2 \; ^4{\rm F}_{J}, with J = 3/2, 5/2, 7/2 and 9/2.
Given the complexity of the electronic structure of W+ the calculations
reproduce the main features of the experimental cross section quite well.Comment: 23 pages, 7 figures, 1 table: Accepted for publication in J. Phys. B:
At. Mol. & Opt. Phy