Time: 4 november 2026, 13.00-14.30
Venue: SDU Classroom U166, Building 44, University of Southern Denmark, Campusvej 55, 5230 Odense M
Registration: No registration needed. Everybody is welcome!
Abstract:
Hunting optical phenomena at the nanometer scale—performing nano-optics—is inherently paradoxical. While optical processes are governed by wavelengths on the order of hundreds of nanometers, the optical response of nanostructures begins to deviate from bulk behavior precisely when their dimensions fall below this scale. Metallic nanoparticles, for instance, sustain plasmon resonances highly sensitive to minute variations in geometry, while in systems such as quantum dots or wells, atomic-scale details become decisive.
Over the past two decades, a range of experimental approaches has emerged to circumvent the optical diffraction limit and access the optical properties of individual nanostructures.
In this talk, I will present a family of techniques based on focused beams of free electrons, as implemented in transmission electron microscopes, to perform optical spectroscopy with nanometer resolution.
I will first discuss electron-only approaches, such as electron energy loss spectroscopy, and their ability to probe phonon-polaritons and plasmonic excitations. I will then introduce photon-based modalities, including cathodoluminescence and electron energy gain spectroscopy, which enable access to properties such as plasmonic chirality and high-Q photonic modes.
Finally, I will present recent developments combining electron and photon detection in coincidence. These approaches provide new insight into plasmonic, photonic, and excitonic excitations, and open the way to nanoscale thermometry with unprecedented spatial and temporal resolution.