Theoretical Study On The Photoelectron Momentum Distribution Of Atoms And Molecules In Elliptically Polarized Laser

The interaction between laser and matter has always been a research topic of wide concern to researchers.When a strong laser pulse acts on an atom or molecule,the electron will be ionized,and the ionized electron wave packets with the same final momentum will interfere with each other,which leads to the formation of various interference patterns in the photoelectron momentum distribution.In this article,we mainly study the vortex patterns in photoelectron momentum distribution of He⁺under the interaction of a pair of counter-rotating ellipticity polarized laser and the molecular photoelectron momentum distributions of H₃²⁺ by an elliptically polarized laser pulse.（1）We theoretically investigate the vortex patterns in photoelectron momentum distribution of He⁺driven by a pair of counter-rotating elliptically polarized laser field.The vortex patterns show the dependence on the ellipticity of the elliptically polarized laser pulse.As the ellipticity decreases,the number of vortex arms in the clear interference patterns gradually decreases.This conclusion is confirmed in both ε₁=ε₂ and ε₁≠ε₂ cases.In addition,we also compare the effect of wavelength of laser pulse on the vortex shape photoelectron momentum distribution.Results show that the number of vortex arms decreases as the wavelength decreases.Finally,the effect of time delay on the photoelectron momentum distribution is discussed.As the time delay increases,the number of vortex arms in the clear interference patterns also increases,and we discuss the physical mechanism of the increase in the number of vortex arms.This result demonstrates a control of vortex interference patterns in the attosecond time scale.The numerical results are analyzed by attosecond perturbation ionization theory.（2）The photoelectron momentum distributions of triangular and linear structure H₃²⁺ molecules under elliptically attosecond laser pulses are investigated theoretically.Firstly,the effect of the ellipticity of laser pulses on the photoelectron momentum distribution of triangular and linear H₃²⁺ molecules is investigated.The results show that with the increase of the ellipticity,the intensity of the photoelectron momentum distribution decreases in the region around the x axis,but increases significantly in the region around the y axis.Secondly,the influence of molecular internuclear distance on the photoelectron momentum distribution is investigated.This phenomenon is well understood in terms of the evolution of the initial photoelectron momentum distribution of molecules.Notably,a clear laser-induced electron diffraction pattern has been found in the photoelectron momentum distribution by adjusting the molecular internuclear distance of linear H₃²⁺ molecule.Finally,we study the influence of molecular orientation angle on the photoelectron momentum distribution.