About possibility of strong coupling between single molecule and surface plasmons

TL;DR

This paper investigates the conditions under which a single molecule can strongly couple with surface plasmons, predicting that such coupling occurs only in the UV range for silver nanoparticles and critically re-evaluates experimental interpretations of molecule-plasmon interactions.

Contribution

It provides a microscopic classical analysis predicting strong coupling conditions and critically assesses previous experimental claims of such coupling in composite layers.

Findings

Strong coupling predicted only in UV range for silver nanoparticles

Experimental data can be explained without assuming strong coupling

Re-evaluation of spectroscopic data interpretations

Abstract

The possibility of strong coupling between a single molecule and surface plasmons is analyzed on the basis of a microscopic classical description. It is predicted that strong single molecule - plasmon coupling can happen for a silver nanoparticle only in the UV range where the real part of the dielectric function of silver approaches a value of -1. A critical view is taken on an interpretation of spectroscopic data of composite layers of dye molecules and a metal film in terms of single molecule-plasmon coupling in a Kretschman configuration in some recent publications. It is shown that experimental results interpreted as a mixed (hybrid) radiation do not reveal strong coupling and can be explained without any coupling effects.