Over the past decade, ultrafast transmission electron microscopy (UTEM) has established itself as an indispensable tool for investigating nanoscale dynamic processes. Photon-Induced Near-field Electron Microscopy (PINEM) leverages the inelastic interaction between free-electron pulses and localized light fields to map transient optical near-fields with atomic-scale spatial precision. However, because optical near-fields in photonic nanostructures typically exhibit pronounced spectral dispersion, traditional narrowband PINEM approaches offer an incomplete picture of these energy-dependent dynamics.
To address this limitation, this study investigates the spectral and spatial dynamics of light–matter interactions in two-dimensional (2D) materials by mapping the electron–light coupling strength (). By employing broadband excitation, we probe the transient interaction landscape, resolving the interplay between excitonic resonances, light scattering, and guided optical modes within the nanostructure. Furthermore, by combining PINEM with Electron Energy-Loss Spectroscopy (PINEM-EELS) in a pump–probe configuration, this approach enables the exploration of diverse material properties and ultrafast phenomena across a broad class of materials.
