A Time-Distinguished Analysis of the Harmonic Structure from a Model Molecular Ion

We present high-order harmonic generation spectra resulted from a single-electron model molecular ion exposed to intense laser fields by numerically solving a one-dimensional time-dependent Schrödinger equation. There are three plateaus in the spectra and the maximal cutoff energy is I_p + 8.5U_p, when the inter-nuclear distance R equals πα₀/2. Here I_p is the ionization potential and U_p = E²₀/(4ω²) is the ponderomotive potential with E₀ and ω being the laser electric field amplitude and the central frequency. The harmonic structures are well interpreted by a modified three-step model in which the effects of the electron reflected by the non-parent ion are stressed.