报告题目：Visualizing Interference Structure with Attosecond Temporal Resolution
报告人：杨玮枫 Weifeng Yang
单位：Department of Physics, College of Science, Shantou University（汕头大学）, Shantou, Guangdong 515063, China
Strong-field photoelectron spectroscopy encodes temporal and spatial information about both the electron and the ion dynamics. To extract this dynamical information, one needs a full understanding of the physical mechanism underlying the complicated interference structures in the photoelectron spectrum. We developed a GQTMC method which could apply to arbitrary values of the Keldysh parameter. Our simulations agree well with both the experimental and TDSE results. It provides an efficient way to probe the interference structures and the underlying electronic dynamics in photoelectron momentum distribution. With the GQTMC method and experimental data,
(i). for the first time, we observed a Freeman resonance time delay in multiphoton ionization of an atom, which is clocked to be 140 attoseconds by using a phase-controlled two-color femtosecond laser pulse.
(ii). A new form of Coulomb-field-driven backward-scattering of photoelectrons in the direction transverse to the laser field is identified to be responsible for a novel and universal curved interference structure in the photoelectron momentum distribution, which has been confused with the holographic interference structure (reported firstly in [Science 331, 61(2011)]) within the strong field physics community for a long time.
(iii). The effect of Coulomb potential and the nonadiabatic subcycle ionization on the photoelectron hologram was investigated.
(iv). A profound ringlike pattern coming from the interplay between the intra- and the intercycle interferences of electron trajectories can be observed in the deep tunneling ionization regime, and an appropriate experimental condition for the observation of the photoelectron holography was provided.