Electron kinetics and emission for metal nanoparticles exposed to intense laser pulses

International audienceA kinetic theory for the interaction of laser radiation with metal nanoparticles embedded in a wide-band-gap dielectric is presented. The formalism is based on the integration of the Boltzmann equation for electrons of an open system, adapted to the description of electron losses from the nanoparticle such as thermionic and photoelectric effects. Differential forms of the electron-electron and electron-phonon collision operators are introduced to perform kinetic calculations beyond the nanosecond time scale. This kinetic model, which also includes nanoparticle-matrix energy transfer, is used to calculate laser energy deposition, redistribution, and electron ejection for nanosecond or picosecond laser-pulse durations in a model system for laser damage investigation; gold nanoparticles embedded in SiO2 glass. Though electron-phonon relaxation times are small compared with laser-pulse duration, an important part of the electron population is found to be driven beyond a typical 10 eV energy. These results suggest that laser absorption by a metal nanoinclusion can create a plasma around the particle