Attosecond nanoplasmonic streaking of localized fields near metal nanospheres

Collective electron dynamics in plasmonic nanosystems can unfold on timescales in the attosecond regime and the direct measurement of plasmonic near-field oscillations is highly desirable. We report on numerical studies on the application of attosecond nanoplasmonic streaking spectroscopy to the measurement of collective electron dynamics in isolated Au nanospheres. The plasmonic field oscillations are induced by a few-cycle near-infrared (NIR) driving field and are mapped by the energy of photoemitted electrons using a synchronized, time-delayed attosecond extreme ultraviolet (XUV) pulse kinetic. By a detailed analysis of the amplitudes and phase shifts, we identify the different regimes of nanoplasmonic streaking and study the dependence on particle size, XUV in streaking spectrograms photoelectron energy, and emission position. The simulations indicate that the near fields around the nanoparticles can be spatiotemporally reconstructed and may give detailed insight into the build-up and decay of collective electron motion.