We present a theoretical study of the main characteristics of two-color photoionization spectra obtained when atoms are subjected to an intense radiation pulse containing the fundamental of an infrared laser and one of its higher harmonics. The calculation is performed by numerical integration of the time-dependent Schrodinger equation for a helium, neon and argon atoms. We present the general properties of the spectra and angular distributions as well as the possible occurrence of interferences between the laser-assisted process and above-threshold ionization. Our results indicate that such interference effects, which can lead to partial coherent control of the photoionization process, can be observed at moderate laser intensities within the reach of currently operated laser and harmonic sources. An agreement with the experimental results for neon photoionization has been obtained.

Abdelkader Makhoute is Professor of Condensed Matter Physics at the Moulay Ismail University, Faculty of Sciences, Meknes-Morocco and is a research associate at International Theoretical Physics, Trieste-Italy and visiting researcher at Free University of Brussels (ULB). He is a coordinating of Laser and Nanophysics Master’s. His research activities concern quantum collision theory, the interaction of intense laser fields with atoms/molecules and dynamics of complex Systems. He has obtained PhD. degree at Free University of Brussels-Belgium (May 1991).