Wavelengths and transition rates for nl–n′l′ transitions in Be-, B-, Mg-, Al-, Ca-, Zn-, Ag- and Yb-like tungsten ions

Abstract

We present a comprehensive theoretical study of atomic characteristics of eight isoelectronic sequences of tungsten ions in a broad range of wavelengths and transitions. In particular, excitation energies, oscillator strengths and transition probabilities are calculated for nl–n′l′ transitions in W70 +, W69 +, W62 +, W61 +, W54 +, W44 +, W27 + and W4 + ions. Atomic structure and radiative characteristics of Be-like ([He]2lnl′, n = 2, 3), B-like ([He]2l2l′2l″), Mg-like ([Ne]3l3l′), Al-like ([Ne]3l3l′3l″), Ca-like ([Ar]3d4l), Zn-like ([Ni]4l4l′), Ag-like [Kr]4d10nl) and Yb-like ([Xe]4f145l6l′) tungsten ions are computed by the relativistic many-body perturbation theory (RMBPT) method. The calculations start from a 1s2 Dirac–Fock potential for Be- and B-like W, from the 1s22s22p6 Dirac–Fock potential for Mg- and Al-like W; from the 1s22s22p63s23p6 and 1s22s22p63s23p63d10 Dirac–Fock potentials for Ca- and Zn-like W, respectively. Evaluation of properties of Ag-like and Yb-like ions starts from a Dirac–Fock potential with only partially filled n = 4 shell (1s22s22p63s23p63d104s24p64d10) and n = 5 shell (1s22s22p63s23p63d104s24p64d104f145s25p6), respectively. First-order perturbation theory is used to obtain intermediate coupling coefficients, and second-order RMBPT is used to determine the matrix elements. The contributions from negative-energy states are included in the second-order E1 matrix elements to achieve agreement between length-form and velocity-form amplitudes. Our calculations present benchmark data for many yet unmeasured properties of tungsten ions and are in particular important in diagnostics of tungsten plasma of a broad range of temperatures as well as for future ITER plasmas.