Laser-produced and tokamak spectra of lithiumlike iron, Fe^23+

Abstract

Spectra of highly ionized iron were generated in a laser-produced plasma and a tokamak. In the spectra from the laser-produced plasma new lines of Fe23+ were observed that were identified as 3s–4p, 3p–4d, and 3d–4f transitions. The measured wavelengths of these lines were combined with measurements of the 2s–2p resonance lines measured in the tokamak plasma and with earlier measurements of n = 2 to n = 3 transitions to yield an improved system of energy levels for Fe23+. The measured wavelengths are compared with ab initio theoretical values calculated with a Dirac–Fock code. With the 4f energy levels, which are nearly hydrogenic, an improved ionization energy of 16 503 000 ± 1400 cm−1 (2046.11 ± 0.17 eV) was determined.