Radiative lifetimes of excited levels in three-electron systems: Ga I, Ge II, As III, Se IV and In I, Sn II, Sb III, Te IV

Comparison of theoretical and experimental lifetimes has been performed for excited levels in the Ga I and In I isoelectronic sequences in order to test the applicability of radiative lifetimes based upon semiempirical calculation methods. The theoretical lifetimes are obtained from (i) calculations using a single-parameter numerical Coulomb approximation, for which a consistent cut-off criterion has been developed, and (ii) published data based upon a parametrised Dirac radial equation. Twenty-five experimental lifetimes for Ge II, As III, Se IV and Sn II, Sb III, Te IV have been measured by means of the beam-foil technique. Good agreement is obtained between theoretical and experimental lifetimes for higher-lying levels, whereas deviations are present particularly for low-lying nd 2 D levels.