We report on detailed investigations of ionization dynamics of a Xe atom exposed to intense 800-nm pulses of 20-fs duration in the extensive intensity range from 10(13)-10(18) W/cm(2). Ion yields of Xe+-Xe20+ were observed as a function of laser intensity and compared with the results from a single active electron based Ammosov-Delone-Krainov model. Unexpected ionization probabilities for lower charge states and no interplay between the inner and outer shells by screening are inferred. Suppression of nonsequential ionization towards higher intensity and few optical cycle regimes is also proved.
Advanced Photon Research Center, KANSAI Research Establishment, Japan Atomic Energy Research Institute, 8-1 Umemidai, Kizu, Kyoto 619-0215, Japan. yamakawa@apr.jaeri.go.jp
