Speaker
Description
Electron energy loss spectroscopy (EELS) and Cathodoluminescence (CL) in a scanning transmission electron microscope (STEM) are now routinely used for investigating the nanoscale variations of optical signals in a variety of systems, and in particular plasmonic ones. Recently, experiments in which the energy loss is detected in coincidence with the subsequent emission of a photon – coined as cathodoluminescence excitation spectroscopy (CLE) (see set-up in figure 1a) – have been performed on plasmonic [1], photonics [2] and semiconducting [1] structures. In the case where the excitations are created in a coherent way by the impinging electron (photonic and plasmonic structures), the observable under measurement is still ambiguous. Is a CLE experiment revealing physics closer to absorption properties (like EELS) or to scattering properties (like CL)? To address this question, we have performed EELS and polarized CL (pCL) in coincidence (pCLE). We have performed spatially resolved EELS, pCL and pCLE experiments (see figure 1b) on chiral plasmonic systems (Born-Kuhn structures, i.e. two staggered silver nano-antennas see figure 1b) which we recently demonstrated to exhibit high local circular dichroism using pCL [3]. In this presentation, the physical description of the polarized CLE signal will be discussed, how it relates to EELS and polarized CL and how it can be used to perform new forms of spectroscopy.
References:
[1] Varkentina, Nadezda, et al. Science Advances, 8(40), eabq4947.
[2] Feist, Armin, et al. Science 377.6607 (2022): 777-780.
[3] Bézard, Malo, et al. arXiv preprint arXiv:2605.26058 (2026).