Electron heating through a set of random levels in the conduction band of insulators induced by femtosecond laser pulses

We develop a theory describing the heating of electrons in crystalline insulators irradiated by high-intensity laser pulses. In agreement with photoelectron yield versus intensity measurements, we assume that electrons are excited into the conduction band from defect layers and traps. The electron dynamics due to direct inter-branch transitions within the conduction band is simulated by solving of time-dependant Schr?dinger equation. The set of levels for this equation is supposed to be random with a distribution function equal to the density of states in the conduction band. The influence of different parameters on the electron heating efficiency is studied. The theory is applied for diamond; the theoretical spectrum is in qualitative agreement with the experimental observations.