Strong-field ionization of plasmonic nanoparticles

Abstract

We modeled strong-field ionization of metal nanoparticles by intense infrared laser pulses, accounting for and distinguishing in photoelectron (PE) momentum distributions the effects of PE correlation, PE--residual-charge interactions, PE rescattering and recombination, and transient laser-induced plasmonic fields. Our numerical results for 5-, 30-, and 70-nm-diameter gold nanospheres and peak laser-pulse intensities of $8.0\ifmmode\times\else\texttimes\fi{}{10}^{12}$ and $1.2\ifmmode\times\else\texttimes\fi{}{10}^{13}\phantom{\rule{4.pt}{0ex}}{\text{W/cm}}^{2}$ show how PE velocity-map images are distinctly shaped by PE Coulomb repulsion, residual-charge accumulations, and plasmonic near fields. In contrast to gaseous atomic targets and dielectric nanoparticles, we find very large PE cutoff energies, for both directly emitted and rescattered PEs, that exceed the incident laser-pulse ponderomotive energy by two orders of magnitude.