[en] Photoelectron spectra emitted by CsI crystals submitted to high frequency laser radiation (800 nm, 40 fs, 1 kHz, 1 TW) have been measured. The emission of electrons with an energy of a few tens of eV, has been observed for light impulses between 0,5 and 3 TW/cm². All these spectra contain 2 bands in the energy range below 5 eV. The most energetic electrons form a plateau slightly structured and bounded by an exponential drop. For 3 TW/cm² impulses this drop is located at 27 eV. The classical electron-photon-phonon model is unable to describe this process. A new model is proposed, this model is based on the direct optical transitions between the different branches of the conduction band. These transitions were not taken into account in previous models. (A.C.)