Collinear Laser-Beam Ion-Beam Measurement of the Mean Lifetime of the Ar Ii 4p'2f-Degrees-7/2 Level
Abstract
The mean lifetime tau of the 4p'F-2(7/2)-degrees level of Ar II has been measured using a variant of the collinear laser-beam-fast-ion-beam spectroscopy technique. Our variant requires no mechanical motion or laser frequency tuning. The result is tau=8.414+/-0.025 ns in agreement with an earlier, comparably precise, measurement based on a crossed laser-ion-beam technique. The result lies above all theoretical calculations.