Strong-field dissociation of CO₂⁺ Van-Hung Hoang¹ and Uwe Thumm¹ ¹Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA

We theoretically investigated strong-field XUV-IR pump-probe dissociative ionization of CO₂. Employing the multi-configurational self-consistent-field quantum-chemistry code GAMESS to ab initio calculate CO₂⁺ adiabatic potential energy surfaces and dipole couplings, we numerically propagated the time-dependent Schrödinger equation for the nuclear motion. Distinguishing the effects of (velocity-dependent) non-adiabatic and external IR-field dipole couplings, we (A) calculated the population of the predissociative C ²Σ_g⁺ state and kinetic energy release (KER) in the O + CO⁺ dissociation channel and (B) investigated the imprint on KER spectra of the nuclear dynamics near the A²Π_u and B²Σ_u⁺ conical intersection. Accounting for all vibrational normal modes (bending, symmetrical and anti-symmetrical stretch), our simulated fragment KER spectra and pump-probe-delay dependent CO⁺ yield oscillation period are in good agreement with the experiment of Timmers et al., Phys. Rev. Lett. 113, 113003 (2014). This agreement persists for reduced-dimensionality calculations with linear molecules (disregarding bending).