Charge-state-specific extreme ultraviolet (EUV) spectra produced from charge exchange collisions between tin ions in charge states from Sn 15+ to Sn 18+ 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 4s 2 4p m− 1 4d–4s 2 4p m− 1 4f+ 4s 2 4p m− 2 4d 2 transitions. However, in addition, a distinct group of lines resulting from 4s 2 4p m− 1 4d–4s 2 4p m− 1 5p (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.