Electron emission from metal surfaces excited by intense femtosecond pulses

Electron emission from a metal surface excited by an intense femtosecond laser pulse can be dominated by thermionic emission due to highly non-equilibrium electron heating process because of the small electronic heat capacity and brief uncoupling between the electron and lattice. Experimental observations of such transient thermionic emission could potentially serve as a diagnostic of peak electron temperature Te. However, their interpretation is difficult because the large electron emission rate introduces tremendous space-charge fields at the surface, which substantially suppress the electron yield and simultaneously distorting the detected electron energy distribution from the initial distribution. In order to understand quantitatively the electron yield and energy distribution and to develop a useful diagnostic technique, the authors present a combined experimental, analytical theory and particle simulation investigation of femtosecond pulse induced electron emission from Al, Ag and W surfaces