# Tailored nanoscale plasmon-enhanced vibrational electron spectroscopy

## TL;DR

This paper demonstrates a novel nanoscale vibrational spectroscopy technique that uses plasmon coupling in silver nanowires to enhance and resolve phonon features in h-BN, revealing strong plasmon-phonon interactions.

## Contribution

It introduces a precise nanowire milling and electron energy-loss spectroscopy method for enhanced vibrational analysis at the nanoscale.

## Key findings

- Resolved hidden bulk phonons in h-BN
- Observed strong plasmon-phonon coupling
- Demonstrated tunable plasmon energy via nanowire length

## Abstract

Vibrational optical spectroscopies can be enhanced by surface plasmons to reach molecular-sized limits of detection and characterization. The level of enhancement strongly depends on microscopic details of the sample that are generally missed by macroscopic techniques. Here we investigate phonons in h-BN by coupling them to silver-nanowire plasmons, whose energy is tuned by modifying the nanowire length. Specifically, we use electron beam milling to accurately and iteratively change the nanowire length, followed by electron energy-loss spectroscopy to reveal the plasmon-enhanced vibrational features of h-BN. This allows us to investigate otherwise hidden bulk phonons and observe strong plasmon-phonon coupling. The new milling-and-spectroscopy technique holds great potential for resolving vibrational features in material nanostructures.