Beam-laser lifetime measurements for low-lying quartet states in Fe ii

Abstract

Radiative lifetimes for seven levels of the z $^{4}\mathrm{\ifmmode^\circ\else\textdegree\fi{}}$, $^{4}$D\ifmmode^\circ\else\textdegree\fi{}, and $^{4}$F\ifmmode^\circ\else\textdegree\fi{} terms of Fe ii have been measured by using laser excitation of a beam of fast ${\mathrm{Fe}}^{+}$ ions. The ratio of the measured lifetime to that calculated from Kurucz's gf values appears to increase systematically with the energy of the levels involved.