Systematic variation of the electron-beam energy in an electron-beam ion tr
ap has been employed to produce soft-X-ray spectra (20 to 60 Angstrom) of A
u with well-defined maximum charge stat es ranging from Br- to Co-like ions
. Guided by large-scale relativistic atomic structure calculations, the str
ongest Deltan = 0 (n = 4 to n' = 4) transitions in Rb- to Cu-like ions (Au4
2+ -Au50+) have been identified.