The first Doppler-shift-free crystal-spectrometer measurement of stationary highly stripped uranium ions from a high-energy electron beam ion trap is presented. Thirteen 2${\mathit{s}}_{1/2\mathrm{-}}$2${\mathit{p}}_{3/2}$ transitions in eight ionization states bteween Li-like ${\mathrm{U}}^{89+}$ and Ne-like ${\mathrm{U}}^{82+}$ are identified and measured with an accuracy as high as 37 ppm, providing benchmarks for testing relativistic correlation and quantum electrodynamic effects in highly charged multielectron ions. A value of 47.39±0.35 eV is found for the 2${\mathit{s}}_{1/2}$ Lamb shift in Li-like ${\mathrm{U}}^{89+}$, in excellent agreement with theory.

• Received 12 March 1993

DOI:https://doi.org/10.1103/PhysRevLett.71.3939