Studies of differential and total photoionization cross sections of carbon dioxide

The photoionization of C${\mathrm{O}}_2$ has been studied using accurate frozen-core Hartree-Fock final-state wave functions. The Hartree-Fock continuum equations were solved using the iterative Schwinger variational method. We present differential and total cross sections for photoionization leading to the $X{}_{}{}^2{}_{}{}^{}\Pi _g^{}{}_{}{}^{}$, $A{}_{}{}^2{}_{}{}^{}\Pi _u^{}{}_{}{}^{}$, $B{}_{}{}^2{}_{}{}^{}\Sigma _u^{+}{}_{}{}^{}$, and $C{}_{}{}^2{}_{}{}^{}\Sigma _g^{+}{}_{}{}^{}$, states of C${\mathrm{O}}_2^{+}$ as well as for oxygen and carbon $K$-shell photoionization. The present cross sections are compared to experimental data and are found to be in generally good agreement. The theoretical cross sections exhibit features due to a narrow shape resonance in those channels where the continuum wave functions have ${\sigma }_u$ symmetry. The relation between these results and experimental cross sections is discussed. The present fixed-nuclei results have also been compared to published theoretical results obtained using the Stieltjes-Tchebycheff moment theory approach and the continuum multiple-scattering method.