Cancellation effects in computed lifetimes of 3s3p n levels for third-row atoms and ions

Abstract

It is well known that calculated transition probabilities values are often unreliable because of cancellation effects resulting from configuration mixing. A typical example is provided by the transitions 3s 23p m −3s3p m+1 for third-row atoms and ions. In fact, the values of the corresponding transition probabilities which are calculated by means of an independent-particle model (such as Hartree-Fock) are generally of the order of 10 to 1000 times larger than the observed data. For the isoelectronic sequences of P I and S I, we have shown, with the use of a parametrized potential, that the mixture of 3s3p m+1 and 3s 23p m−1 3d configurations is responsible for the most important part of the discrepancy. The general procedure used for calculating transition probabilities has been described already in a previous paper given at the Second International Conference of Beam Foil Spectroscopy. However, while for the noble gases, the angular part of the wave functions was obtained by a least squares fit of energy levels, the wave functions (including configuration mixing) here are determined completely from the central potential. The agreement between observed (especially by the beam-foil technique) and calculated lifetimes for the 3s3p m+1 levels is generally good for the cases where comparisons are possible.