About possibility of strong coupling between single molecule and surface plasmons

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.