Relativistic R-matrix calculations for the photoionization of W61+ ions

Direct and resonant photoionization of Al-like W61+ ions from their ground state 1s22s22p63s23p 2P1/2 and four lowly excited states 1s22s22p63s23p 2P3/2, 1s22s22p63s3p2 4P1/2,3/2, and 1s22s22p63s3p2 2D5/2 is studied by using the multiconfigurational Dirac–Fock method and the relativistic R-matrix method. Emphasis is placed upon exploring direct and resonant ionization limits and also upon identifying possible resonance channels of W61+ ions. To do so, the photoionization cross sections are calculated with the use of the Dirac Atomic R-matrix Code. For the ground-state photoionization, the direct and resonant ionization limits are obtained, and the identified resonance peaks are found to be associated with the resonances 1s22s22p63s3lnl′ and 1s22s22p63p3lnl′ (l,l′=p,d) at a level of fine-structure energy level or configuration. For the excited-state photoionization, however, although the respective direct ionization limits are obtained, the resonant ionization limits and resonance peaks are hardly distinguishable due to much more densely spaced resonance peaks and complex resonance structure. It is expected that the present work could fill the vacancy of studies on the photoionization of W61+ ions and be helpful to the diagnosis and simulation of the thermonuclear fusion plasmas together with other available photoionization data of tungsten ions with other charge states.