Measuring the quantum efficiency of single radiating dipoles using a   scanning mirror
  Using scanning probe techniques, we show the controlled manipulation of the radiation from single dipoles. In one experiment we study the modification of the fluorescence lifetime of a single molecular dipole in front of a movable silver mirror. A second experiment demonstrates the changing plasmon spectrum of a gold nanoparticle in front of a dielectric mirror. Comparison of our data with theoretical models allows determination of the quantum efficiency of each radiating dipole. 
B. C. Buchler, T. Kalkbrenner, C. Hettich, and V. Sandoghdar