Photoelectron spectra after multiphoton ionization of Li atoms in the one-photon Rabi-flopping regime

We calculate two-dimensional photoelectron momentum distributions and energy spectra after multiphoton ionization of Li atoms subject to intense laser fields in one-photon Rabi-flopping regime. The time-dependent Schr\"{o}dinger equation is solved within the single-active-electron approximation using a model potential which reproduces accurately the binding energies and dipole matrix elements of the Li atom. Interaction with the external electromagnetic field is treated within the dipole approximation. We show that the Rabi oscillations of the population between the ground $2s$ state and the excited $2p$ state in the one-photon resonance regime are reflected in the energy spectra of emitted photoelectrons which manifest interference structures with minima. Transformations of the interference structures in the photoelectron energy spectra caused by the variation of the laser peak intensity and pulse duration are analyzed.

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