We theoretically study the photoelectron momentum distributions from multiphoton ionization of a model lithium atom over a range of laser wavelengths from 500 nm to 700 nm by numerically solving the time-dependent Sch...We theoretically study the photoelectron momentum distributions from multiphoton ionization of a model lithium atom over a range of laser wavelengths from 500 nm to 700 nm by numerically solving the time-dependent Schr ¨odinger equation. The photoelectron momentum distributions display many ring-like patterns for the three-photon ionization, which vary dramatically with the change of the laser wavelength. We show that the wavelength-dependent photoelectron energy spectrum can be used to effectively identify the resonant and nonresonant ionization pathways. We also find an abnormal ellipticity dependence of the electron yield for the(2+1) resonance-enhanced ionization via the 4d intermediate state, which is relevant to the two-photon excitation probability from the ground state to the 4d state.展开更多
Tunneling is one of the most fundamental and ubiquitous processes in the quantum world.The question of how long a particle takes to tunnel through a potential barrier has sparked a long-standing debate since the early...Tunneling is one of the most fundamental and ubiquitous processes in the quantum world.The question of how long a particle takes to tunnel through a potential barrier has sparked a long-standing debate since the early days of quantum mechanics.Here,we propose and demonstrate a novel scheme to accurately determine the tunneling time of an electron.In this scheme,a weak laser field is used to streak the tunneling current produced by a strong elliptically polarized laser field in an attoclock configuration,allowing us to retrieve the tunneling ionization time relative to the field maximum with a precision of a few attoseconds.This overcomes the difficulties in previous attoclock measurements wherein the Coulomb effect on the photoelectron momentum distribution has to be removed with theoretical models and it requires accurate information of the driving laser fields.We demonstrate that the tunneling time of an electron from an atom is close to zero within our experimental accuracy.Our study represents a straightforward approach toward attosecond time-resolved imaging of electron motion in atoms and molecules.展开更多
基金supported by National Key Research and Development Program of China (Grant No. 2019YFA0308300)the National Natural Science Foundation of China (Grant Nos. 12021004 and 61475055)。
文摘We theoretically study the photoelectron momentum distributions from multiphoton ionization of a model lithium atom over a range of laser wavelengths from 500 nm to 700 nm by numerically solving the time-dependent Schr ¨odinger equation. The photoelectron momentum distributions display many ring-like patterns for the three-photon ionization, which vary dramatically with the change of the laser wavelength. We show that the wavelength-dependent photoelectron energy spectrum can be used to effectively identify the resonant and nonresonant ionization pathways. We also find an abnormal ellipticity dependence of the electron yield for the(2+1) resonance-enhanced ionization via the 4d intermediate state, which is relevant to the two-photon excitation probability from the ground state to the 4d state.
基金the National Key Research and Development Program of China(Grant No.2019YFA0308300)the National Natural Science Foundation of China(Grant Nos.11874163,61475055,and 12021004).
文摘Tunneling is one of the most fundamental and ubiquitous processes in the quantum world.The question of how long a particle takes to tunnel through a potential barrier has sparked a long-standing debate since the early days of quantum mechanics.Here,we propose and demonstrate a novel scheme to accurately determine the tunneling time of an electron.In this scheme,a weak laser field is used to streak the tunneling current produced by a strong elliptically polarized laser field in an attoclock configuration,allowing us to retrieve the tunneling ionization time relative to the field maximum with a precision of a few attoseconds.This overcomes the difficulties in previous attoclock measurements wherein the Coulomb effect on the photoelectron momentum distribution has to be removed with theoretical models and it requires accurate information of the driving laser fields.We demonstrate that the tunneling time of an electron from an atom is close to zero within our experimental accuracy.Our study represents a straightforward approach toward attosecond time-resolved imaging of electron motion in atoms and molecules.
