# Direct Observation of Infrared Plasmonic Fano Antiresonances by a Nanoscale Electron Probe

## TL;DR

This study demonstrates the use of advanced STEM techniques to directly observe infrared plasmonic Fano antiresonances at the nanoscale, revealing new insights into plasmonic interactions in nanostructures.

## Contribution

The paper presents the first direct experimental observation of infrared plasmonic Fano antiresonances in individual nanostructures using STEM and EELS.

## Key findings

- Resolved Fano antiresonances in individual nanostructures.
- Identified weak coupling regime between plasmonic modes.
- Demonstrated STEM's capability for nanoscale plasmonic spectroscopy.

## Abstract

In this Letter, we exploit recent breakthroughs in monochromated aberration-corrected scanning transmission electron microscopy (STEM) to resolve infrared plasmonic Fano antiresonances in individual nanofabricated disk-rod dimers. Using a combination of electron energy-loss spectroscopy (EELS) and theoretical modeling, we investigate and characterize a subspace of the weak coupling regime between quasi-discrete and quasi-continuum localized surface plasmon resonances where infrared plasmonic Fano antiresonances appear. This work illustrates the capability of STEM instrumentation to experimentally observe nanoscale plasmonic responses that were previously the domain only of higher resolution infrared spectroscopies.