Femtosecond thermionic emission from metals in the space-charge-limited regime
Journal of the Optical Society of America. B, Optical physics
We study femtosecond-laser-pulse-induced electron emission from W(100), Al(110), and Ag(111) in the subdamage regime (1-44 mJ/cm 2 fluence) by simultaneously measuring the incident-light reflectivity, total electron yield, and electron-energy distribution curves of the emitted electrons. The total-yield results are compared with a space-charge-limited extension of the Richardson-Dushman equation for short-time-scale thermionic emission and with particle-in-a-cell computer simulations of
... ulations of femtosecond-pulsed-induced thermionic emission. Quantitative agreement between the experimental results and two calculated temperaturedependent yields is obtained and shows that the yield varies linearly with temperature beginning at a threshold electron temperature of -0.25 eV The particle-in-a-cell simulations also reproduce the experimental electronenergy distribution curves. Taken together, the experimental results, the theoretical calculations, and the results of the simulations indicate that thermionic emission from nonequilibrium electron heating provides the dominant source of the emitted electrons. Furthermore, the results demonstrate that a quantitative theory of space-charge-limited femtosecond-pulse-induced electron emission is possible.