Abstract

The phenomenon of above threshold ionization (ATI) has been under intense investigation for nearly 10 years now. During this time not only have many diverse experimental and theoretical investigations been reported, but several major conferences have been held as well with the professed goal of achieving some consensus in the interpretation of the basic phenomena. Still, the ATI research community remains largely fragmented and confused about the basic physics and is in danger of dividing into separate camps. In this paper I argue that the fundamental ideas necessary to understand the experimental results in ATI have already been put forward by many authors, often in other fields. For example, theorists interested in nonlinear Compton scattering worked out the form of the interaction of high intensity light with electrons, and plasma physicists wrote down the consequences of this interaction for real-life measurements of kinetic energies of electrons produced in focused, high-intensity beams. Many investigators concerned with the nonlinear interaction of high-intensity light on bound electron systems had to understand the concept of optical field ionization and have subsequently applied this knowledge to the measurement of spectra obtained in multiphon ionization of molecules with IR light. I will show that if the relevant conclusions of these and other works are combined with the body of experimental and theoretical work from the ATI community, a rather simple and appealing description of ATI emerges, one which emphasizes the universality of its nature.

© 1986 Optical Society of America