Absolute measurement of the resonance lines in heliumlike vanadium on an electron-beam ion trap

trap are reported. The 1 s2p 1P1!1s 2 ,1 s2p 3P2!1s 2 ~1s2p 3P1!1s 2 and 1s2p 3P0!1s 2 ! blend and 1s2s 3S1!1s 2 transitions are 5205.10 6 0.14 eV, 5189.12 6 0.21 eV, 5180.22 6 0.17 eV, and 5153.82 6 0.14 eV, respectively. This agrees with recent theoretical calculations and the experimental precision lies at the same level as the current uncertainty in theory ~0.1 eV!. These measurements represent a 5.7-8% deter- mination of the QED contribution to the transition energies and are the most precise measurements of heli- umlike resonance lines in the Z519- 31 range. The measurement of the 1s2s 3S1!1s 2 transition is also sensitive to the 1 s2s 3S1 QED contribution at the 40% level. The intensity of the strong 1 s2p 3 P1!1s 2 component of the blend compared to the total blend intensity is 94%612%. This is in accord with current theoretical predictions but disagrees with an earlier reported ratio.