Auger decay of the photoexcited 2pnl Rydberg series in argon

The 2pns(nd) inner-shell photoexcited resonance states in argon are studied using a combination of optical potential, multichannel quantum defect theoretical, and R-matrix methods. Optical potential inclusion of the infinite number of core decay channels correctly accounts, in an implicit manner, for the physical broadening of resonances within the 3p and 3s cross sections, but highly asymmetric resonance features remain. Comparison with experimental results is made, showing good qualitative agreement in the resonance profiles. The quantitative differences are due to unconverged theoretical resonance energies and to discrepancies in the background cross sections. Fine-structure-resolved cross sections and angular distribution parameters are investigated in the present calculations, revealing major qualitative departure from nonrelativistic predictions; these features should be observable in high-resolution measurements. @S1050-2947~99!09308-7#