Study On The Ionization Property Of Atoms In The Intense Laser Field

As a basic phenomenon of strong field physics,strong field ionization has been widely concerned for decades.The ionization of atom in the intense laser field plays an important place in the strong field ionization.Study on the ionization property of atom,deepens our understanding for strong field physics and helps us to find more novel strong field phenomenons.According to the theory of strong field theory,the following three aspects are studied:The classical trajectory,the photoelectron momentum distributions?PMDs?and the photoelectron angular distributions?PADs?.The results indicate that the atomic ionization properties are affected by the carrier envelope phase?CEP?and optical cycle of strong laser fields.We prove that strong field ionization significantly depends on the ultra-short laser pulse.The three aspects of research results are given as follows.Firstly,we calculate the classical trajectories by using classical orbit monte carlo method?CTMC?.Find that the ionization trajectory depends on the laser pulse.And,the emitting direction reverse with the carrier envelope phase ₀?=?.Besides,we also find photoelectrons reverse when the optical cycle of laser pulse is increased.Secondly,we theoretically investigate the detachment of negative hydrogen ion in circularly polarized monochromatic and bichromatic laser fields by calculating the PMDs.We find that the PMDs are controlled by the electric field of the laser pulse.For the circularly polarized bichromatic laser field,the PMDs are inversion asymmetric,but symmetric about a certain axis.The emission directions of the photoelectrons vary with the electric field shape,that is to say,the emitting directions of the photoelectrons vary with the CEP,which decide the electric field of laser pulse.The maximum position of the PMDs change with the CEP.Finally,we study the PADs of hydrogen atoms with n-cycle circularly polarized laser pulse with GAC theory.We find that the PADs with one-cycle laser pulse is inversion asymmetric and the distribution is not affected by photoelectron energy,but affected by the carrier envelope phase significantly.The PADs remains in the form of inversion asymmetry with the increasing of the optical cycle,however,we find the affection by photoelectron energy is more and more obvious.The PADs are almost perfectly symmetrical circle pulse with twelve optical cycles especially for low-order above-threshold ionization?ATI?peaks.The phenomena show that if the number of cycles of the laser pulse is more larger,the ionization behaviors of atom will extend to that of atom in an infinitely monochromatic plane wave.We can get the characteristics of CEP,and the ionization property through the research with hydrogen atoms in strong fields of the classical trajectory,the PMDs and the PADs,Meanwhile,The research provide a solid foundation for the research for novel phenomenon.