Time-resolved ionization of the hydrogen atom in strong laser fields

We use the strong field approximation to study the single-photon ionization of the hydrogen atom in the time domain. During the interaction of the laser pulse and the atom, the electron is pumped to the Volkov state and has a widely energy distribution at the beginning of the laser pulse. With the time evolution, only the photon-electron with the energy (h) over bar omega - I-P is survived, where omega is the laser angular frequency, and I-P is the ionization potential of the atom. Therefore We observed how the energy spectrum of the ionized electron builds in the time domain.