Laser-induced Processes of Diatomic Molecules: Homonuclear vs. Heteronuclear Species

Abstract

We investigate high-order above-threshold ionization (HATI) and high-order harmonic generation (HHG) of homonuclear and heteronuclear diatomic molecules using modified molecular strong-field approximation (MSFA) and Stark-shift-corrected MSFA respectively. We present our results for N2 and CO molecules. Their initial highest occupied molecular orbitals (HOMO) are characterized by 3σg and 5σ symmetry respectively, as for heteronuclear species parity property gerade or ungerade is no longer relevant. N2 and CO HATI and HHG spectra for different molecular orientation with respect to laser polarization axis, and for different values of the electron or photon energies and emission angle, clearly reflect influence of the electron-density distribution symmetry of the HOMO. Prominent difference between these spectra is the absence of the left-right symmetry in HATI spectra for paralel orientation and selection rules violation in HHG spectra for CO. Spectra for CO could be reconstruct with contributions that accounts for ionization from the C atom only.