Measurements and calculations of metastable level lifetimes in Fe X , Fe XI , Fe XII , Fe XIII , and Fe XIV

Lifetimes of metastable levels in the ground term of Fe ions within the 3s3p, k51 – 5, isoelectronic sequences have been measured. These measurements were performed utilizing ions that were selected by mass to charge ratio while transported from an electron cyclotron resonance ion source to a Kingdon ion trap, where they were captured and then confined for periods of up to 2.1 s. During this storage period, selected emission wavelengths of transitions from metastable levels in the visible or near-ultraviolet spectral regions were isolated using interference filters, and the time-dependent fluorescence intensities were measured using a photomultiplier tube. Measurement precisions on the order of 2% were achieved in favorable cases. The measured lifetimes are t~Fe X, 3sp P1/2)513.6460.25 ms, t~Fe XI, 3s 3p D2)59.8660.22 ms, t~Fe XII, 3s3p P3/2)51.8560.24 ms, t~Fe XII, 3s 3p P1/2)54.3860.42 ms, t~Fe XII, 3s 3p D3/2)520.35 61.24 ms, t~Fe XIII, 3s3p D2)56.9360.18 ms, and t~Fe XIV, 3s 3p P3/2)517.5260.29 ms. These results are compared with existing and with new theoretical calculations, which have estimated uncertainties on the order of 10–25 %.