Interpretation of the spectra of a laser-irradiated Au plasma in the 3.0–4.0-Årange

The spectrum of a laser-produced gold plasma (3.0–4.0 Å) was interpreted by Kiyokawa et al. [Phys. Rev. Lett. 54, 1999 (1985)] as due to multiple inner-shell vacancy states of ${\mathrm{Au}}^{26+}$–${\mathrm{Au}}^{32+}$. New extended observations (3.5–6.1 Å) obtained from a similar Au plasma with a better resolution lead to unambiguous identification of several emission lines of ${\mathrm{Au}}^{51+}$, and an alternative theoretical interpretation of all spectral features from 3.0–3.8 Å is proposed in terms of unresolved transition arrays (3d-5f and 3d-6f types) of ${\mathrm{Au}}^{52+}$–${\mathrm{Au}}^{48+}$.