Identification of 4d–5p transitions in the spectra of Sn XV–Sn XIX recorded from collisions between Sn ions and He

Abstract

Charge-state-specific extreme ultraviolet (EUV) spectra produced from charge exchange collisions between tin ions in charge states from Sn15+ to Sn18+ and rare gas target atoms using an ECR (electron cyclotron resonance) source have been recorded at Tokyo Metropolitan University. At low target gas pressures, the spectra were produced by single collision and capture events, and in each case they were dominated by intense emission near 13 nm. In the spectra of Sn XV–Sn XIX this emission has been shown to arise from 4s24pm−14d–4s24pm−14f + 4s24pm−24d2 transitions. However, in addition, a distinct group of lines resulting from 4s24pm−14d–4s24pm−15p (2 ⩽ m ⩽ 6) transitions centred near 11.5 nm in Sn XV was seen to shift to shorter wavelength with increasing ionic charge, and the strongest lines were identified by comparison with atomic structure calculations. These identifications are the subject of the present work.