Exchange Effect In Ionization And High-harmonic Generation Of Molecular

In recent decades,with the continuous development of intense laser pulses,it be-comes possible to change and control the motions of electrons in atoms and molecules.Strong-field ionization and high-order harmonic generation has attracted our great atten-tion especially.In this paper,we mainly study on ionization and High-harmonic gen-eration of molecular based on the strong field approximation ionization theory and the Lewenstein's high-order harmonic generation?HHG?model,respectively.Firstly,the strong field approximate?SFA?ionization theory are briefly reviewed,then the static exchange effect is added to the existing strong field approximation model of molecular,and a new ionization model of molecular was established,and the model is applied to N₂and CO₂.The results of the ionization rate of the modles are compared showing that the ionization rate increases obviously,but differently in intensity versus the alignment angle?between the molecular main axis and the laser-field polarization direction.Secondly,we have a brief introduction about the Lewenstein theory,after that a new model was established by adding exchange effect to time-dependent dipole moment of Lewenstein's model.We apply the new model to N₂and CO₂.For N₂,The spectral cal-culated by the new model exhibits no changes in the overall structure but the intensity is found enhanced compared with the original obtained from the SLIMP package.We examine the yields of harmonics integrated from the 19-th to 23-rd harmonics for N₂?the25-th to 29-rd harmonics for CO₂?versus alignment angle?.We find that the difference between the models is largest at?=0^???=38^??indicating that the static exchange be-tween the HOMO and other orbital modifies the spectra at 0^??38^??.In order to distinguish the long and short paths in HHG,the method of time-frequency analysis has been used to study the H atom and CO₂in two-color fields,which will continue to be applied to molecules deeply in the future.Finally,we have a deep consideration on the research direction in the future on the basis of summing up the previous research work.