Exploring the limits of single emitter detection in fluorescence and   extinction
  We present an experimental comparison and a theoretical analysis of the signal-to-noise ratios in fluorescence and extinction spectroscopy of a single emitter. We show that extinction measurements can be advantageous if the emitter is weakly excited. Furthermore, we discuss the potential of this method for the detection and spectroscopy of weakly emitting systems such as rare earth ions. 
Gert Wrigge and Jaesuk Hwang and Ilja Gerhardt and Gert Zumofen and   Vahid Sandoghdar