Direct and indirect pathways in strong field atomic ionization dynamics.

With the help of a suitably chosen momentum-space analysis, we study some of the basic mechanisms governing the physics of the processes occurring when atoms are submitted to intense infrared laser pulses, with peak intensities 10(14) W cm(-2)</=I(max)</=10(15) W cm(-2). This intensity range is especially interesting because two highly nonlinear atomic processes, namely, above threshold ionization and high-order harmonic generation, take place with significant probabilities. Several issues regarding the dynamics of these processes are resolved, with special attention devoted to the mechanism leading to the ejection of the photoelectrons in this intensity range.