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Resolving the blueshift in calculations of the EUV spectrum of multiply charged tin ions

M. L. Reitsma1, J. Sheil1,2, O. O. Versolato1,2, E. V. Kahl3, and J. C. Berengut4

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Phys. Rev. A 114, L020802 – Published 26 August, 2026

DOI: https://doi.org/10.1103/v557-qqql

Abstract

We report ab initio relativistic calculations on the complex open shell Sn12+ highly charged ion, a prototypical plasma ion relevant for extreme ultraviolet (EUV) nanolithography. Previous calculations of EUV emissivity in tin plasmas consistently generate a spectrum in which the region of peak emissivity is blueshifted relative to experiment. By optimizing our numerical methods to take full advantage of modern, high-performance CPU architectures, we are able to completely saturate the configuration interaction within the n=4 shell. Coupled with a thorough treatment of core-valence correlation we resolve the blueshift, finding a surprisingly large influence of highly excited states on the spectrum that is dominated by multiply excited states.

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Phys. Rev. A 114, L020802– Published 26 August, 2026
  • Received 13 May 2026
  • Accepted 27 July 2026
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