THE PECULIAR DECAY OF THE 2S2P3P4D7/2 LEVEL IN F V

This paper discusses a lifetime measurement for the 2s2p3p 4D7/2 level in F(V) performed using the beam-foil technique. The cascade situation for this level is highly unusual in that it leads to a multiexponential decay curve where the component representing the 4D7/2 level itself has a negative amplitude. A non-linear formulation of the ANDC method for cascade correction is used in the decay analysis, and the advantages of this procedure are discussed. In particular we point out the possibility to couple the results of successive ANDC analyses along a cascade chain. From the measured decay curves the ratio of the initial populations of the 3d 4F9/2 and 3p 4D7/2 levels is determined to 0.76 +/- 0.07.