  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.
