Dissociative ionization of CO2 in XUV pump and IR or visible probe pulses

Following the sudden single ionization of CO₂ in ultrashort extreme ultraviolet pump pulses, after exposure to delayed 780- or 400-nm probe-laser pulses, we propagate the coupled nuclear motion in CO₂⁺ on the A0.16em0ex²Πᵤ, B0.16em0ex²Σᵤ⁺, C0.16em0ex²Σg⁺, a0.16em0ex⁴Σg^-, and b0.16em0ex⁴Πᵤ potential-energy surfaces of the excited molecular cation, including all vibronic degrees of freedom. We calculate potential-energy surfaces, diabatic couplings, and probe-laser-induced dipole couplings ab initio and heuristically model spin-orbit couplings. Based on our numerical results, we scrutinize the relative importance of diabatic, dipole, and spin-orbit couplings during the dissociation of CO₂⁺ into O(³Pg)+CO⁺(X0.16em0ex²Σ⁺) and O⁺(⁴Sᵤ)+CO(X0.16em0ex¹Σ⁺), provide rovibrational-excitation distributions of the CO⁺ fragments, and discuss pump-probe-delay-dependent kinetic-energy-release spectra. Addressing the nuclear dynamics near the conically intersecting A0.16em0ex²Πᵤ and B0.16em0ex²Σᵤ⁺ states of CO₂⁺, we reproduce the valence-hole oscillation period of 115 fs measured by Timmers et al. [Phys. Rev. Lett. 113, 113003 (2014)]. In addition, we predict and characterize, in terms of quantum beats between specific stationary vibronic states, a 3.1-ps fragment-yield oscillation.