Odd-even harmonic generation from oriented CO and NO molecules within strong-field approximation

Abstract

Recently, the pure-even high-order harmonic generation (HHG) has theoretically found by the ab initio methods for CO molecules interacting with an intense laser. An examination of this phenomenon using the analytical approach such as the Lewenstein model, and for another polar molecular with other symmetry is needed. In this study, we theoretically investigate the odd-even harmonic generation from the CO and NO molecules in the linearly polarized laser field by using the Lewenstein model. Firstly, we confirm entirely the pure-odd and pure-even emission from CO whose molecular axis is perpendicular to the polarization direction of the laser. Secondly, we show that the odd-even behavior of the HHG spectra from NO is similar to that from the CO molecule. The HOMO's symmetricity of the linear molecule does not change the odd-even property of the HHG spectra.