Accurate theoretical simulation of attosecond transient absorption spectroscopy in N₂

We report theoretical investigation of attosecond transient absorption spectroscopy (ATAS) of molecular nitrogen. Our calculations are based on the numerical solution of the couple-channel time-dependent Schrodinger equation with the account for the accurate potential energy surfaces together with the non-adiabatic and dipole couplings. Furthermore, the effect of molecular alignment with respect to the polarization directions of the extreme ultraviolet (XUV) pump and near-infrared probe lasers are also fully considered. We find improved agreements with all the main features of the earlier experimental measurements by Warrick et al, Chem. Phys. Lett. 683, 408 (2017). Our results indicate that ATAS measurements are capable of probing potential energy surfaces of the target dark states.