INVESTIGATION OF LASER-INDUCED STRUCTURES IN MULTIPHOTON IONIZATION OF MAGNESIUM

We examine the effect of the excitation of an autoionizing state on el ectron spectra resulting from multiphoton-ionization. We study the cas e of above threshold three-photon ionization of magnesium in the regio n of the 3p3d P-1(o) resonance, with conditions similar to a two-colou r experiment recently performed. The electron spectrum is compared to the partial spectrum corresponding to the region located just above th e threshold (which is populated through two-photon absorption from a p robing laser). The calculations confirm the experimental observations, a laser induced continuum structure (LICS) is observed in this partia l spectrum The interference process in examined in detail and a Fano-l ike parametrization of the two-photon ionization electron profile is p roposed.