  The coupling of nanostructures with emitters opens ways for the realization
of man-made subwavelength light emitting elements. In this article, we
investigate the modification of fluorescence when an emitter is placed close to
a nanostructure. In order to control the wealth of parameters that contribute
to this process, we have combined scanning probe technology with single
molecule microscopy and spectroscopy. We discuss the enhancement and reduction
of molecular excitation and emission rates in the presence of a dielectric or
metallic nanoparticle and emphasize the role of plasmon resonances in the
latter. Furthermore, we examine the spectral and angular emission
characteristics of the molecule-particle system. Our experimental findings are
in excellent semi-quantitative agreement with the outcome of theoretical
calculations. We express our results in the framework of optical nanoantennae
and propose arrangements that could lead to the modification of spontaneous
emission by more than 1000 times.
