Fig. 5: Angular dependence of the effect of the coupling between the ionic states.

a, b Differential cross section for one-photon ionisation of CO₂⁺ at photon energy 29 eV into the \({C}^{2}{\Sigma }_{g}^{+}\) state by field polarised parallel with the molecular axis (a) and perpendicular to it (b). The units are arbitrary, but consistent between the panels. The red and blue arrows indicate the laser polarisation direction and the molecular axis (MA), respectively. c, d RABBIT time delays τ_B for the \({B}^{2}{\Sigma }_{u}^{+}\) state integrating over the full solid angle (blue solid lines) or along the polarisation direction of the XUV and IR fields (green dash-dotted lines) with (c) and without (d) inclusion of the ionic coupling. For these simulations, the attochirp was set to zero.