Measurement of the QED energy shift in the1s22p3∕2–1s22s1∕2x-ray transition in Li-likePb79+208

Abstract

The $1{s}^{2}2{p}_{3∕2}--1{s}^{2}2{s}_{1∕2}$ x-ray transition in the Li-like ${\mathrm{Pb}}^{79+}$ has been observed using the Tokyo electron beam ion trap at the University of Electro-Communications. The contribution of QED $(\ensuremath{-}24.99\ifmmode\pm\else\textpm\fi{}0.10\phantom{\rule{0.3em}{0ex}}\mathrm{eV})$ to the $1{s}^{2}2{p}_{3∕2}--1{s}^{2}2{s}_{1∕2}$ transition in $^{208}\mathrm{Pb}^{79+}$ is determined and compared with different calculations. The measurement was made by calibrating the Pb line using the Lyman-$\ensuremath{\alpha}$ lines of the H-like $S$ and the $1s4p\phantom{\rule{0.2em}{0ex}}^{1}P_{1}--1{s}^{2}\phantom{\rule{0.2em}{0ex}}^{1}S_{0}$ transition in the He-like $P$.