On-command enhancement of single molecule fluorescence using a gold nanoparticle as an optical nano-antenna

TL;DR

This study demonstrates how a gold nanoparticle can be precisely positioned to significantly enhance the fluorescence of a single molecule, revealing insights into plasmonic effects on emission.

Contribution

It provides the first direct experimental evidence of on-command fluorescence enhancement using a gold nanoparticle nano-antenna with nanometer precision.

Findings

Fluorescence intensity increased by over 20 times

Excited state lifetime shortened by 20-fold

Role of particle plasmon resonance confirmed

Abstract

We investigate the coupling of a single molecule to a single spherical gold nanoparticle acting as a nano-antenna. Using scanning probe technology, we position the particle in front of the molecule with nanometer accuracy and measure a strong enhancement of more than 20 times in the fluorescence intensity simultaneous to a 20-fold shortening of the excited state lifetime. Direct comparison with three-dimensional calculations allow us to decipher the contributions of the excitation enhancement, spontaneous emission modification, and quenching. Furthermore, we provide direct evidence for the role of the particle plasmon resonance in the modification of the molecular emission.