Ionization of nanoparticles by supershort moderate-intensity laser pulses

Abstract

This paper presents the results of the numerical modelling of electron emission from metallic nanoparticles under the action of femtosecond laser pulses with peak intensity from tenths of a terawatt to tens of terawatts per square centimeter. The model takes into account the effects of the excitation of the valence electrons of the nanoparticle due to multiphoton absorption, described by the Keldysh model, and the increase of the ionization potential due to the generation of positive charge in the nanoparticle during electron emission. The transition from multiphoton ionization to tunnel emission as the laser-radiation intensity increases is demonstrated, and it is shown that Fowler’s model and its modification give a substantial underestimate of both the peak photoemission rate and the total emission current.