One- and two-photon double ionization of beryllium with ultrashort ultraviolet laser fields

The interaction between the beryllium atom and short laser fields is treated on the basis of the nonrelativistic time-dependent Schrodinger equation. We calculate total cross sections and electron energy distributions for the double ionization of the valence electrons through one- and two-photon absorption. We introduce a model potential to represent the 1s(2) core. The emphasis is put on the double ionization of the valence electrons in the context of ultrashort pulses. Results will be also presented for the ionization of the inner electrons.