ANGULAR-DISTRIBUTION PARAMETERS AND R-MATRIX CALCULATIONS OF AR3S(-1)-]NP RESONANCES

Angle-resolved photoelectron spectra have been measured with 6 meV pho ton resolution for the Ar 3s(2)3p(6) --> 3s3p(6)np (n = 4-16) autoioni zation resonances in the energy range between 26 and 29.3 eV, using sy nchrotron light from an undulator beamline of the Advanced Light Sourc e. Photoelectron angular distribution parameters beta have been parame trized according to the prescription of Kabachnik and Sazhina and have been compared with R-matrix calculations similar to those of Burke an d Taylor. The agreement was found to be very good. We have also analys ed the cross section shape for the first six resonances, confirming pr evious measurements performed for the lower resonances, and compared t hem with various calculations.