In the field of strong field physics, the interaction between strong field laser pulses and atoms and molecules has been a hot topic for several decades. Atoms and molecules will be ionized in the strong field laser pulses. The ionized electrons have a certain possibility to return to the nucleus and to be scattered by the nucleus. The scattering processes record the information of the nucleus. Similarly to the optical holography, the strong field photoelectron holography is recognized as the interference of nonscattering trajectories (reference wave) and those rescattering trajectories (signal wave). Using this photoelectron holography, the phase of atomic scattering amplitude has been successfully extracted and the initial phase distribution of the molecular tunnel wave packet has been reconstructed. The recent experimental results show that the low-energy interference structure (LES) and the high-energy interference structure (HES) are quite different, but the physical origin for the formation of the low-energy interference structure is not very clear.
The ultrafast optics group led by Prof. Peixiang Lu presents the photoelectron momentum distribution of atom in a midinfrared laser field using the quantum-trajectory Monte Carlo (QTMC) model. By studying the formation of photoelectron momentum distribution ionized within a half cycle time window, it is shown that the origin of the LES is quite different from that of the HES. It is demonstrated that the inner spider structure comes from the interference between the triple-forward scattering trajectories and the nonscattering trajectories. This study provides the theoretical guidance for the application of photoelectron holography in the field of atomic and molecular physics.
This work is published on Opt. Express Vol. 24, No. 24, 27726 (2016). This work was supported by the National Natural Science Foundation of China under Grant Nos. 61405064 and 11234004 and the Fundamental Research Funds for the Central University, HUST: 2016YXMS012.
Figure Two-dimensional photoelectron momentum distribution for the ionization time windows of (a) whole laser pulse and (b) half laser cycle.