Electron-electron and electron-phonon relaxation in metals excited by optical pulse

A short overview of theoretical models for the description of the relaxation processes in metals excited by a short laser pulse is presented. The main effort is given to description of different processes which are taking place after absorption of the laser pulse. Widely used two-temperature model is discussed and the conditions of applicability of this model are identified. Various approaches for solving the Boltzmann kinetic equations are discussed. It is identified that in the case of low excitation limit the relaxation is determined by the emission of phonons by photoexcited electrons. The possibility to obtain the value of the electron phonon coupling constant from experiments is discussed. (author)