Core-level photoelectron and Auger shape-resonance phenomena in CO, CO2, CF4, and OCS

Abstract

Cross sections and angular-distribution asymmetry parameters were measured directly for C(KVV) Auger electrons and C 1s photoelectrons from CO, CO2, CF4, and OCS, O(KVV) Auger electrons and O 1s photoelectrons from CO and CO2, and S(LVV) Auger electrons and S 2p photoelectrons from OCS using synchrotron radiation. The measurements were made in the photon-energy ranges 270–350, 545–680, and 160–190 eV, respectively. Shape resonances were observed in all of these molecular systems. The cross-section results are compared with previous experimental data obtained by electron energy-loss measurements, electron–ion coincidence results, and photoabsorption studies. The asymmetry-parameter results are the first of their kind for these molecular core levels. The present results are compared with available theoretical predictions obtained from Stieltjes–Tchebycheff imaging techniques, Hartree-Fock static-exchange calculations, and the multiple-scattering method.