Ionization and stabilization of atoms in a high-intensity,low-frequency laser field

The dynamics of a model silver atom in the strong radiation field of a Ti:sapphire laser is studied in the Keldysh parameter regions γ ⩾ 1 and γ ⩽ 1. It is found that in the entire range of Keldysh parameter variations, along with ionization, the efficient excitation of Rydberg states of the atom with principal quantum numbers n = 6−14 is observed. A Rydberg wavepacket appearing in this case proved stable with respect to ionization; i.e., the atomic system in strong low-frequency electromagnetic fields becomes stable with respect to ionization. The physical reasons behind the stabilization are discussed.