K-shell photoionization of CO: II.Determination of dipole matrix elements and phase differences

Abstract

Using the experimental angular distributions of photoelectrons from theK-shells of an oriented CO molecule reported in a companion paper, wehave performed a so-called complete experiment and determined 18dynamical parameters (ten moduli of transition moments and eight phasedifferences) for the O K-shell, and 16 dynamical parameters (nine moduliof transition moments and seven phase differences) for the C K-shell, andcompared them with the results of our calculations in therelaxed-core Hartree-Fock (RCHF) approximation. The agreementbetween theory and experiment is only qualitative, thereforethe model has to be improved by including electroncorrelations. From the analysis of experimental data we provedthat the σ* shape resonance is due to not onlythef-wave, as was widely believed earlier, but is due to approximatelyequal contributions of three partial waves with 1⩽l⩽3 for the CK-shell, and four partial waves with 0⩽l⩽3 for the O K-shell,with a rather substantial contribution of other partial waves with l⩽5. From the analysis of the transition moments determined from theexperiment it follows that several Cooper minima are likely to exist inpartial photoionization cross sections, in particular, in the C 1sσ→εsσ and in the O 1sσ→εdσ transitions.