Radiation controlled energy of photoelectrons produced by two-color short pulses

Abstract
We report on numerical results of energy spectra of photoelectrons emitted by irradiating a hydrogen atom with the superposition of two pulses. The spectra have been obtained by numerical integration of the time dependent Schrödinger equation. The highest frequency component of the pulse has been assumed to have low intensity and such a frequency that a single photon may ionize the atom. Its duration has been assumed to lie in the range of subfemtoseconds. The lowest frequency component that redistribute the energy of the ionized electrons has an higher intensity and duration of few femtoseconds. We find that when the field are aligned, the electron energy spectra strongly depend on the time lag of the fields, on the carrier-envelope relative phase of the lowest frequency pulse, and on the duration of the X-ray pulse. Moreover it has been found that by changing the angle between the direction of the low and high frequency fields significant modifications to the spectra occur that could be used to measure the relative orientation of the fields.