IQI Weekly Seminar

In the first part of this talk, I will present some recent work on the interaction of plasmonic chiral matter with both circularly polarized light and vortex electron beams. For light, we compare the calculations based upon multiple scattering theory with recent observations of circular dichroism in plasmonic nanoparticles assembled using DNA origami. For electrons, we predict strong dichroism in the electron energy-loss spectroscopy (EELS) signal by using vortex beams. These electrons carry orbital angular momentum that can be exchanged in the interaction with chiral plasmons. We also predict a dichroic response when probing chiral biomolecules, which suggests the use of these vortex for resolving different enantiomers.

In the second part of the talk, I will address the phenomenon of plasmon-mediated electron energy gain, in which the interaction of swift electrons with strong evanescent light fields scattered by a nanostructure (e.g., by excitation of a plasmon by an external laser beam) can produce energy gains in the electrons and stimulated photon emission. This electron-light interaction can provide detailed information on the optical properties of the sampled nanostructures in the time and frequency domains. I will show that, taking advantage of plasmonic resonances, spectroscopy can be performed by varying the illumination frequency at remarkably low light intensities.