Nanoscale imaging of surface plasmons by ultrafast electron microscopy

Ultrafast Electron Microcopy (UEM) is one powerful tool to study the ultrafast dynamics of light-matter interactions in physics, chemistry and materials science with temporal resolution of femtoseconds. We established one state-of-art UEM scientific platform at the Center for Nanoscale Materials (CNM), Argonne National Laboratory. UEM at Argonne has been used to investigate ultrafast dynamics of plasmons, phonon, and phase transitions. Besides the capabilities of imaging and diffraction, the UEM here was equipped with one GIF spectrometer, which enables it to work in energy filtering mode and characterize the near field of surface plasmon resonance. Surface plasmons, collective oscillating charge at the surface of metals or interface of metals/dielectrics under light excitation, are among the most attractive candidates for next-generation information revolution due to their ability to confine electromagnetic field and empower strong coupling of light and matter beyond the diffraction limit. The nanoscale imaging of surface plasmons is critical for the biological sensing and SERS methods, plasmonics and nanophotonics, waveguide, quantum information processing. Here, we investigated the excitation and manipulation of Localized Surface Plasmon Resonances (LSPR) at surface of metal nanoparticles and Surface plasmon polaritons (SPPs) at the interface of metal and dielectric by UEM and their dependence on laser wavelength, polarization, fluence at nanometer scale and femtoseconds time scale.