Angular-distribution parameters andR-matrix calculations of Ar resonances

Abstract
Angle-resolved photoelectron spectra have been measured with 6 meV photon resolution for the Ar (n = 4 - 16) autoionization resonances in the energy range between 26 and 29.3 eV, using synchrotron light from an undulator beamline of the Advanced Light Source. Photoelectron angular distribution parameters have been parametrized according to the prescription of Kabachnik and Sazhina and have been compared with R-matrix calculations similar to those of Burke and Taylor. The agreement was found to be very good. We have also analysed the cross section shape for the first six resonances, confirming previous measurements performed for the lower resonances, and compared them with various calculations.