Gap plasmonics of silver nanocube dimers

TL;DR

This paper theoretically studies gap plasmons in silver nanocube dimers, revealing how tunneling affects plasmon modes and contrasting with previous experimental findings.

Contribution

It provides new insights into the effects of tunneling on gap plasmons in silver nanocube dimers, challenging prior experimental interpretations.

Findings

Red-shift of bonding mode saturates with decreasing gap

Tunneling causes damping and slight blue-shift of modes

No low-energy charge transfer plasmon mode observed

Abstract

We theoretically investigate gap plasmons for two silver nanocubes coupled through a molecular tunnel junction. In absence of tunneling, the red-shift of the bonding mode saturates with decreasing gap distance. Tunneling at small gap distances leads to a damping and slight blue-shift of the bonding mode, but no low-energy charge transfer plasmon mode appears in the spectra. This finding is in stark contrast to recent work of Tan et al. [Science 343, 1496 (2014)].