Generation And Modulation Of Vortex Photoelectrons

As a product of strong laser and atomic ionization,photoelectrons have been used as probes to study the ultrafast dynamics process in ionization.In recent years,the scheme of using reverse time-delayed circular polarization pulses to produce vortex-shaped photoelectron momentum distributions in the polarization plane has been proposed,which has attracted much attention because of its extreme sensitivity to the excitation laser field.In the field of ultrafast dynamics,a large number of physical quantities that are difficult to be detect directly in experiments can be more or less characterized by the vortex photoelectron momentum distribution.In this thesis,we conduct research on the generation,regulation and application of vortex photoelectrons.The specific contents are as follows:(1)Reviewed the research course of ultrafast dynamic process,especially the distribution of photoelectron momentum,leading to the research status of vortex photoelectron momentum distribution,and expounding the research significance of vortex photoelectron.(2)Combined with the method of numerically solving the time-dependent Schr?dinger equation(TDSE),the Qprop method for quickly solving TDSE by using the surface flux means is emphatically introduced,and then the improvements we made to simulate the momentum distribution of vortex photoelectron.(3)By analyzing the quantum process of the generation of vortex photoelectron,we discussed the influence of time delay,sequence order,relative carrier envelope phase and wavelength on the distribution of vortex photoelectron momentum one by one.With a slightly change of time-delay between the two beams of counter-polarized laser pulses,we theoretically observed the difference in the angle of rotation between different energy positions on the vortex arm of photoelectric energy distribution.During the transition from single-photon to two-photon ionization,the forking and merging of photoelectron vortex arms were observed.For the first time,we theoretically studied the effect of the atomic magnetic quantum number sign on the vortex photoelectron momentum distribution,and the modulation effect of the difference in ionization rate that the magnetic quantum number sign depends on the photoelectron momentum distribution.(4)Combined with the generation of vortex photoelectricity and the control effect of different physical quantities,the typical application scenarios of vortex photoelectron were analyzed.In addition to the application of measurement,we proposed a photoelectron momentum distribution that uses two pairs of reverse-delay circularly polarized laser ionized atoms to generate uniformly cut vortex arms,because of its high controllability,it is expected to be a special electron source.