Ultrafast Dynamics Of Atoms Frustrated Double Ionization Driven By Strong Laser Fields

Double ionization of atoms and molecules driven by a strong laser field provides an effective way to study ultrafast electron dynamics.It has been one of the hot topics in the field of strong field physics,attracting the attention of research groups at home and abroad.There are many physical processes involved in the frustrated double ionization of strong field atoms.The study of FDI(frustrated double ionization)is helpful for further understanding the electron dynamic behavior during double ionization.Based on classical ensemble theory model,frustrated double ionization of atoms in the strong laser field is studied.This paper mainly includes three aspects:(1)Electron dynamics of frustrated double ionized in magnesium atoms driven by elliptic polarized light is investigated.The results show that the dynamic behavior of electron emission in FDI and DI processes is strongly dependent on the ellipticity.With the increase of ellipticity,the distributions of final state momentum of FDI and DI are mainly concentrated near zero momentum along the secondary axis direction,and gradually move away from zero momentum.As a result,in the case of large ellipticity,the final state momentum distributions of FDI and DI show an obvious elliptic structure in the electric field plane.The tracing analysis shows that with the increase of the ellipticity,the energy transferred by the returning electron to the parent ion during the recollision process decreases,which reduces the energy obtained by the ionized electron after the recollision,and leads to a more obvious suppression of the electron yield near zero momentum in FDI relative to DI.(2)Laser pulse duration dependent electron dynamics of frustrated double ionized argon atoms.The theoretical results show that the momentum distribution of the final state of the single electron along the polarization direction of the laser field mainly concentrates in two non-zero regions and presents an obvious asymmetric distribution.The asymmetry of asymmetrical distribution decreases with the increase of laser pulse duration.The inverse analysis shows that when the laser pulse width is narrow,the collision process mainly occurs through the short orbit,and the ionized electron mainly exits on the same side of the electric field peak,resulting in a significant asymmetric distribution of the momentum distribution of the final state of the electron.With the increase of laser pulse duration,the collision process tends to occur through the long orbit,and more ionized electrons are emitted at different sides of the electric field peak.As the pulse duration increases,the asymmetry of momentum distribution decreases.(3)The electron dynamics of frustrated double ionized argon atom driven by a parallel two-color laser pulses.The results show that the dominant FDI ionization channel and the main quantum number can be controlled by changing the laser wavelength ratio of the two-color field.With the increase of wavelength ratio,the dominant FDI channel changed from FDI1(incoming electrons are bound)channel to FDI2(the electrons that are touched are bound)channel.The larger the wavelength ratio,the higher the Rydberg state of the FDI event and the larger the principal quantum number.Inversion analysis shows that with the increase of wavelength ratio,although the collision energy of the incoming electron increases,the dominant FDI channel changes from FDI1 to FDI2 due to the lower energy transfer efficiency in the collision process.