4d photoabsorption spectra of Sn II and Sn IV in the 30–65 eV region

EUV photoabsorption spectra of tin ions Sn II and Sn IV have been recorded using the dual laser-produced plasma (DLP) technique in the 30–65 eV region. It is known from previous studies by Lysaght et al (2005 Phys. Rev. A 72 014502), in the 30–100 eV domain, that gradual 4f contraction along the isonuclear sequence of Sn I through Sn IV results in a redistribution of the oscillator strength from the continuum to the pseudo-discrete 4d → f channels, with many intense absorption lines dominating the spectra of Sn IV. Using Hartree–Fock with configuration interaction calculations allows us to successfully account for, and permits identification of, pseudo-discrete 4d → np, nf features within the spectra of Sn II and Sn IV.