Transitions in Na III

Abstract

The work of Blackford and Hibbert(1994 At. Data Nucl. Data Tables 58 101-64)has been extended to provide oscillator strengths and transition probabilitiesfor J→J' transitions amongst n = 2 and n = 3 levels of Na III. Configuration interaction wavefunctions,obtained with the code CIV3 in the Breit-Pauli approximation,and with additional correlation effects, have been constructed.Further semi-empirical corrections to the wavefunctions (`fine-tuning') are made so as to bring the calculated energydifferences into agreement with the corresponding experimental values.It is demonstrated that in LS coupling there is excellent agreement between lengthand velocity forms of the oscillator strengths, and for most multiplet transitions the length form agrees wellboth with the earlier calculations of Blackfordand Hibbert and with the results of the Opacity Project. The recent claims (Kelleher et al 1999 Contributed papers, Sixth Int. Coll. on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas pp 83-86)of major discrepanciesbetween the CIV3 calculations and the Opacity Project (OP) data are shown to be due largely to the use of simple algebraictransformations of the LS-coupled OP data to produce line oscillator strengths in making the comparison. However, it is shown thatfor certain transitions, fine-tuning makes a substantial difference to the calculated oscillator strengths, so that the presentwork is a significant improvement over the previous calculations.