Lifetime of the metastable 2P1/2 state of F-like Ar9+ isolated in a compact Penning trap
Samuel M. Brewer, Joan M. Dreiling, Nicholas D. Guise, Shannon M. Hoogerheide, Aung Naing, Joseph N. Tan
Multiple-ionized atoms can be captured at low energy in a compact Penning trap, allowing the isolation of a single charge state to measure the radiative lifetime of an atomic state that decays via weakly allowed transitions. Such a measurement is reported here for the radiative decay lifetime of the metastable 2P1/2 state in flourine-like Ar9+ wherein the n = 2 shell has only one vacancy (hole) in a 2p orbital. Highly-ionized atoms are extracted from an electron beam ion trap (EBIT) and guided into the ion capture apparatus. Upon capturing the Ar9+ ions, light from the magnetic-dipole (M1) transitions are detected with a photomultiplier tube (PMT) and counted with a multichannel scaler. Using this technique, the radiative lifetime of the metastable 2P1/2 state in Ar9+ 1s2 2s2 2p5 is measured to be Tau = 9.39 +/- 0.09 ms, with a 1% relative uncertainty.
Physical Review A (Atomic, Molecular and Optical Physics)