Laser-Intensity Effect on the Configuration Interaction in Multiphoton Ionization and Autoionization

It is shown that the laser intensity modifies the configuration mixing of the ground state, intermediate states, and autoionizing states in multiphoton ionization and autoionization. To illustrate the intensity effect on autoionization, a calculation is presented for three-photon ionization of the Sr atom near the $\mathrm{}\left(5p6s\right)\mathrm{}{}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}$ autoionizing resonance in a range of laser intensities employed in recent experiments.