Studies of differential and total photoionization cross sections of carbon dioxide

The photoionization of CO₂ 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 X²Πg, A²Πᵤ, B²Σᵤ⁺, and C²Σg⁺, states of CO₂⁺ 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 σᵤ 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.