Enhanced light emission from plasmonic nanostructures by molecules

TL;DR

This paper models the interaction between plasmonic nanostructures and molecules, revealing that molecular excitation enhances background emission and local fields, which impacts surface-enhanced spectroscopy analysis.

Contribution

It introduces a quantum cavity model showing that molecular interactions significantly enhance background emission and local fields in plasmonic nanostructures.

Findings

Background emission is enhanced with molecular Raman scattering.

Molecular excitation increases local fields around nanostructures.

Background fluctuations are mainly due to molecular induced fields.

Abstract

Interaction between plasmonic nanostructures and molecules is modeled based on the concept of quantized optical cavity for surface enhanced Raman scattering process. We have found that the background emission from plasmonic nanostructures is not constant as speculated ordinarily, it is enhanced accompanying with the molecules Raman scattering. The plasmonic nanostructures not only scatter elastically the energy coupling from the molecules excited states, but also radiate it inelastically as surface plasmon emission partly resulting an enhanced background. According to single nanoparticle experiments, the model reveals that the background fluctuations is mainly due to the induced field of the molecules, which increases the local field felt by the nanostructures that was often overlooked in the past. These findings suggest considering the plasmonic nanostructures and molecules as a hybrid entity to analyze and optimize the surface enhanced spectroscopy.