Theoretical transition probabilities and lifetimes in noble gas spectra

Starting from a previous theoretical study on some Ne I transitions, we investigate the problem of the calculation of transition probabilities and lifetimes in noble gas spectra. For transition probabilities, the general procedure is the following: a) least squares fit (including some effective operators) of energy levels for obtaining the angular part of wave functions, b) calculation of the radial part of the wave functions by means of a parametrized potential, c) partial evaluation of the second order effects on transition probabilities with the use of the effective operator formalism. When the comparison is possible, the agreement between calculated and observed transition probabilities is rather good in view of the precision and the scatter of experimental data. However, the accuracy of the theoretical results, estimated by means of an hypervirial theorem, reduces very quickly from Ne I to Xe I and is very poor for low frequency transitions connecting highly excited levels. Consequently, for evaluating lifetimes, it is generally sufficient to use a very simple method which avoids most of intermediate coupling calculations.