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

The spectrum of a laser-produced gold plasma (3.0--4.0 A{}) was interpreted by Kiyokawa et al. [Phys. Rev. Lett. 54, 1999 (1985)] as due to multiple inner-shell vacancy states of Au²⁶⁺--Au³²⁺. New extended observations (3.5--6.1 A{}) obtained from a similar Au plasma with a better resolution lead to unambiguous identification of several emission lines of Au⁵¹⁺, and an alternative theoretical interpretation of all spectral features from 3.0--3.8 A{} is proposed in terms of unresolved transition arrays (3d-5f and 3d-6f types) of Au⁵²⁺--Au⁴⁸⁺.