Electric quadrupole and magnetic dipole transition probabilities within the ground configuration of F+
The radiative lifetime of the 2s22p4 1S0 level in F+ has been measured by time-resolved observations of both strong (though electric-dipole forbidden) decay branches: the electric quadrupole (E2) transition (~80% branch) to the 2s22p4 1D2 level and the magnetic dipole (M1) transition (~20% branch) to the 2s22p4 3P1 level. We observed the fluorescence associated with both transitions from a population of F+ ions circulating in a heavy-ion storage ring. Our result for the F+ 2s22p4 1S0 level lifetime of 420+/-12 ms provides a benchmark for theory. Moreover, although the calculated lifetimes vary by more than 20%, the calculated branching fractions vary by less than 4% and 7% for the 1S0-->1D2 E2 and 1S0-->3P1 M1 transitions, respectively. Using our measured lifetime and the calculated branching fractions, we report semiempirical transition probabilities for the 1S0-->1D2 E2 and 1S0-->3P1 M1 transitions of 1.90 s-1+/-7% and 0.50 s-1+/-9%, respectively.