Investigation On Photoelectron Dispersion Relationship On Metal Surface Based On Attosecond Photoelectron Spectrogram

The ultrafast motion of electrons in matter occurs at the time scale of attoseconds(1attosecond=10^-18seconds).Directly tracking the ultrafast motion of electrons on this ultrashort time scale can find and deepen the understanding of the physical mechanism at the electronic level,and then solve problems or develop new applications by manipulating the ultrafast motion of electrons.In the past decade,the generation of attosecond pulsed light sources based on high-harmonic radiation of atomic gases has provided an unprecedented tool for humans to directly probe electron ultrafast dynamics with attosecond ultrashort time precision.At the same time,the emission process of electrons from atomic bound state to continuous state through optical excitation is one of the most basic quantum processes,which provides the simplest prototype for measuring the photoelectron emission process in attosecond time accuracy by using attosecond photoelectron spectrogram technology based on extreme ultraviolet attosecond pulse pump-infrared laser pulse probe.The development of attosecond photoelectron spectrogram technique transfers the study of electronic energy dispersion relations in solids from frequency domain to time domain.This paper mainly studies the photoelectron emission time and energy dispersion relation on metal surface based on attosecond photoelectron spectrogram.1.In this paper,by constructing a one-dimensional metal surface model,the distribution of local potential and non-local potential inside the metal is introduced in detail.By solving the time-dependent Schr?dinger equation,the specific numerical values of the photoelectron emission delay from different layers of atoms are obtained.The result has deepened our understanding of the potential energy structure inside the metal,and gained some profound insights into the study of the photoelectron emission process on the metal surface.Therefore,we can further research the scale relation between the photoelectron transport time and the observable photoemission emission delay in the solid,and obtain the influence of the potential energy depth and lattice width on the energy dispersion relation in the solid model.2.Based on the recent theoretical research results,this paper reveals a scaling relation between the photoelectron transport time in the single-crystal metals and their observable photoemission time.Such scaling relation depends on the energy dispersion of photoelectrons inside the metals.Previous model employs uniform field,which can only simulate linear energy-momentum dispersion relation.In order to describe the real metal potential more accurately,we employ periodic potentials to represent the potentials of photoelectrons inside metals.The photoelectron spectrogram is obtained by numerical calculation of quantum mechanics,and the functional relation between the photoemission time extracted from attosecond photoelectron spectrogram and the potential well depth and transported metal thickness is obtained.The variation of photoelectron transport time with metal thickness is nonlinear.When the potential well depth reduces from-10 e V to-5 e V,the nonlinearity is more significant.We attribute this phenomenon to the fact that the energy-momentum relation inside the metal strongly depends on the specific form of the metal potential energy.This work has important guiding significance for the study of photoelectron energy dispersion relation on metal surface based on attosecond photoelectron spectrogram.