Recently Sn and Xe ions attract a considerable attention in developing extreme ultra-violet (EUV) light sources which can emit a light of 13.5nm wavelength. This precise wave length for the light source comes from a requirement of the design for the optical system of a lithography machine. Nishihara et. al. [1] has observed EUV spectra from Sn ions in a tin-plasma. Their spectra consists of a broad peak spread over a wide range of wavelength region including 13.5nm in which the 4d-4f transitions in Sn ions play a major role for the emission. To analyze the experimental spectra, an appropriate plasma model with accurate atomic data for the structure of ions in the plasma is needed.
　To obtain reliable atomic data for Sn and Xe ions, we have carried out calculations of excitation energies in the atomic systems with the three atomic structure codes, that is, the relativistic configuration-interaction (RCI) code with the Gaussian type function (GTF) by Koc, et. al. [2], the RCI one with the Slater-type function (STF) by Kagawa et. al. [3] and the finite difference MCDF code by Desclaux and Indelicato[4]. Calculated results with the RCI-GTF code for excitation energies in Sn ions are compared with those of the RCI-STF and the MCDF methods. Discrepancy of excitation energies with the two RCI results between the GTF and STF basis sets is observed. The discrepancy arises from the smallness of the STF set used in the RCI calculation of Kagawa. On the other hand the RCI-GTF results for the transition energy are consistent with MCDF ones. Results for Xe ions will be given in the poster of the conference.

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