THE 1909 A INTERCOMBINATION LINE IN C-III

The configuration interaction code CIV3 is used to calculate the A-val ue for the 1909 angstrom 2s2 S-1(0)-2s2p P-3(1)o intercombination line in C III. An extensive calculation of valence shell correlation is au gmented by the inclusion of core polarization effects both explicitly through further configurations with one or both Is orbitals replaced b y correlation orbitals, and also by the use of model potentials. Our r ecommended value of 104 +/- 4 s-1 for the A-value lies somewhat lower than the experimentally determined value of 121 +/- 7 s-1. We have est imated the expected error in our work by considering the extent of the convergence of our calculation. We also calculated the resonance tran sition and obtain an oscillator strength in excellent agreement with e xperiment.