Theory of multiphoton multielectron ionization of xenon under strong 93-eV radiation.

We present a theoretical interpretation of recent experimental results on multiphoton multiple ionization of xenon by soft-x-ray radiation of photon energy approximately 93 eV and intensity up to 10(16) W/cm2 [A. A Sorokin, Phys. Rev. Lett. 99, 213002 (2007)]. The data are interpreted within multiphoton perturbation theory, taking into account the spatiotemporal distribution of the radiation. Multiphoton cross sections have been obtained through a technique of scaling, with occasional adjustment to the data, provided the two prove to be compatible. Whatever discrepancies between theory and experiment persist can be reasonably attributed to some uncertainty in the experimental conditions and possibly to the value of some cross sections, without, however, any evidence for nonperturbative behavior.