Effect of the Stark shift on the low-energy interference structure in strong-field ionization

An improved quantum trajectory Monte Carlo method involving the Stark shift of the initial state, Coulomb potential, and multielectron polarization-induced dipole potential is used to revisit the origin of the low-energy interference structure in the photoelectron momentum distribution of the xenon atom subjected to an intense laser field, and resolve the different contributions of these three effects. In addition to the well-studied radial finger-like interference structure, a ring-like interference structure induced by interference among electron wave packets emitted from multi-cycle time windows of the laser field is found in the low energy part of the photoelectron momentum spectrum. It is attributed to the combined effect of the Coulomb potential and Stark shift. Our finding provides new insight into the imaging of electron dynamics of atoms and molecules with intense laser fields.