High harmonic generation from pre-ionized H2 in ultrashort intense laser fields

Effects of the laser pulse wavelength and intensity on the high harmonic generation (HHG) production from the ionic and homolytic pre-ionization transient states of the two-electron H2 system exposed to ultrashort intense laser pulses are studied by solving the time-dependent Schrodinger equation. It is found that for the populated homolytic species in each half cycle of the laser pulse having enough strength, a pair of strong and weak HHG radiations are produced simultaneously. For the populated ionic species divided into two regions, in each half cycle, one of the ionic regions has a strong radiation and the other ionic region has a weak HHG radiation. The HHG spectra of the homolytic and ionic species are almost the same, except that in some limited parts of the HHG spectrum, one of them dominates the other.