4d-4f unresolved transition arrays of xenon and tin ions in charge exchange collisions

Abstract

Abstract. Extreme ultra-violet emission spectra of multiply charged Xe and Sn ions are measured following the electron capture in collisions with He. After the assumption of singleelectron capture, we have found that the wide range of charge states, Sn 10+ to Sn 14+ for tin ions, and Xe 11+ to Xe 17+ for xenon ions, have the prominent emissions at 13.5 and 11.0 nm, respectively. These emissions are attributed to the 4d-4f unresolved transition arrays in comparison with the results of theoretical calculations by using the HULLAC code.

Plasma-Related Atomic Physics with an Electron Beam Ion Trap

“…The UTA emission around 11 nm is found for energies between 250 and 650 eV. Judging from the energy dependence, xenon ions with charge states of 11-22 are considered to be responsible for the UTA emission, which is consistent with previous observations [35,36]. In addition, the line emissions at 16.5 nm and 17.5 nm can be identified as transitions in Xe 24+ and Xe 25+ , respectively [20].…”

“…10 (a) shows the EUV spectrum of Xe obtained with the Compact Helical System (CHS) plasma [34]. Strong band-like emission due to unresolved transition array (UTA) [35] is found around 11 nm. In addition, sharp lines are found, including prominent lines at around 16.5 nm and 17.5 nm.…”

The atomic model of the Sn plasmas for the EUV source

“…We see energy levels converge after including sufficient CI, and spectral profile agrees well with those observed in the charge exchange spectroscopy (CXS) [9]. Therefore, we used calculated level energies and radiative rates in the collisional radiative model, however transition wavelengths are corrected according to the observed shift between Hullac code and CXS.…”

Modeling of the Atomic Processes and Photo Emission of the Plasmas for the EUV Source

“…Therefore, we determined the wavelength of the most important 4d-4f transitions by independent measurement. Using the charge exchange spectroscopy (CXS), each single charge state of Sn ions was selected from those produced in the ECR ion source, and the EUV emission spectrum after the charge exchange collision with He or Xe gas is observed 7) . Experiments were repeated from Pd-like to Kr-like ions, and broad unresolved transition arrays (UTA's) were observed, which were identified as 4d-4f, 4d-5p and 4d-5f transitions.…”