Accurate wavelengths of resonance lines in Zn-like heavy ions

Using an electron-beam ion trap and a flat-field spectrometer, the extreme ultraviolet resonance lines of Zn-like ions of Yb, W, Au, Pb, Th, and U were observed and their wavelengths measured with greatly improved accuracy. The results are compared to those from laser-produced plasmas and to theory, and significant differences are found. PACS Nos.: 32.30.Jc, 39.30.+w