A. I. Magunov

Laser-induced resonance trapping in atoms

The coupling of two autoionizing states or of a discrete and an autoionizing state by a strong laser field is studied analytically as well as numerically. The motion of the complex energies is traced as a function of the field strength for different field frequencies and atomic parameters. Most interesting is the critical region where a crossing (or an avoided crossing) of the trajectories occurs. At this critical field intensity, level repulsion in the complex plane occurs. With further increasing intensity, the complex energies move differently. When the resonances are coupled mainly via one common continuum, resonance trapping dominates, i.e. a short- and a long-lived resonance state are formed (level repulsion along the imaginary axis). When, however, the direct coupling dominates, level repulsion along the real axis takes place. Population trapping (defined by a vanishing decay width of one of the states at finite intensity) results from the interplay of the direct coupling of the states and their coupling via the continuum. We also studied the corresponding variation of the cross section for ionization of a laser-driven atom by the probe field.

Fano resonances in the overlapping regime

The line shape of resonances in the overlapping regime is studied by using the eigenvalues and eigenfunctions of the effective Hamiltonian of an open quantum system. A generalized expression

Laser-induced continuum structures and double poles of the S-matrix.

{q}_{k}(E)

Strong laser field effects in autoionization.

for the Fano parameter of the resonance state k is derived that contains the interaction of the state k with neighbored states

Avoided level crossing and population trapping in atoms

lensuremath{ne}k

Laser-induced effects for overlapping autoionizing rydberg states of xenon

via the continuum. It is energy dependent since the coupling coefficients between the state k and the continuum show a resonancelike behavior at the energies of the neighbored states

Influence of the laser-induced continuum structure on cross sections of the over threshold scattering of photons on atom

lensuremath{ne}k.

Laser-induced optical activity in range of Rydberg autoionizing states of xenon

Under certain conditions, the energy dependent

Angular distribution and polarization of photons during resonant above-threshold scattering on an atom

{q}_{k}(E)

Interference of laser-induced resonances in the continuous structures of a helium atom

are equivalent to the generalized complex energy independent Fano parameters that are introduced by Kobayashi et al. in analyzing experimental data. Long-lived states appear mostly isolated from one another in the cross section, also when they are overlapped by short-lived resonance states. The