Multielectron effect in the strong-field ionization of aligned nonpolar molecules

Abstract

We revisit strong-field ionization of aligned ${\mathrm{O}}_{2}, {\mathrm{CO}}_{2}$, and ${\mathrm{CS}}_{2}$ molecules in light of recent advances in the field of strong-field physics, in particular the inclusion of multielectron polarization in the numerical solution of the time-dependent Schr\"odinger equation (TDSE) within the singe-active-electron approximation. Multielectron polarization is modeled by the introduction of a long-range induced dipole term based on the polarizability of the cation, and a field at short distances that counteracts the applied external field and leads to a vanishing time-dependent interaction within a certain cutoff radius. For the probed molecules, the main effect of including multielectron polarization is the reduction of the total ionization yields (TIYs), and for molecules with large polarizability of their cation (${\mathrm{CO}}_{2}$ and ${\mathrm{CS}}_{2}$), the alignment angle of maximum TIY will shift. The photoelectron momentum distributions and above-threshold ionization spectra show little imprint of the multielectron polarization associated with the long-range part of the laser-induced dipole potential. For ${\mathrm{CO}}_{2}$ and ${\mathrm{CS}}_{2}$, the inclusion of multielectron polarization and the associated induced dipole potential in the TDSE model gives alignment-resolved distributions of total ionization yields which are in better agreement with the available experimental results.