Effect of the Corrected Ionization Potential on the HHG Transition Rate in a Linearly Polarized Laser

Abstract

In this paper, we theoretically described the influence of the ponderomotive and the Stark shift on the highorder harmonic generation's transition rate for the cases of noble and alkali atoms in nonrelativistic, linearly polarized laser field. To describe harmonic generation, we used the analytical formula by Frolov et al. which is derived for a weakly bound electron in the tunneling limit and modified it in way to include mentioned effects. We showed that the inclusion of these effects affects the high-order harmonic generation's rate and that for the same conditions, the intensity of the alkali harmonics were considerably weaker compared to the intensity of noble harmonics. Also, the Stark shift for the alkali atoms induces not only decrease of the peak heights i.e. decrease of the ionization yield, but also the peak broadening. At the end, we analyzed the influence of the beam shape on the behavior of obtained theoretical curves. We considered two types of laser field shape, Gaussian and Lorentzian. It is shown that the high-order harmonic generation's rate depends on the spatial distribution of laser beam profiles.