Reconstruction of attosecond beating by interference of two-photon transitions on the lithium atom with Rabi oscillations

We present numerical simulations of the reconstruction of attosecond beating by interference of two-photon transitions (RABBITT) on lithium by solving the three-dimensional time-dependent Schr??dinger equation. In our scheme, the infrared (IR) field couples the 2s and 2p states of lithium and leads to the Rabi oscillations of populations between these two states. We analyzed the RABBITT phases of the two peaks in the Rabi-oscillation-induced Autler-Townes splittings. Our results show that the relative phase between these two peaks changes with the photoelectron energy and depends on the intensity of the IR field. Moreover, in the angle-resolved RABBITT measurement, the phases of the two peaks depend differently on the emission angle of photoelectrons. These behaviors are traced back to the different initial phases of the electron wave packets emitted from the dressed 2p states and the competition among different ionization channels.