Experimental analysis of recoil effects induced by fluorescence photons

The momentum transfer to a scatterer from fluorescence photons was detected using an optical system that permits one to simultaneously measure the radiation force exerted on and fluorescence emission from the scatterer. The core of this technique is a partially metal covered dielectric bead optically trapped in a liquid with dye molecules. Fluorescence emission from the volume that includes the bead is measured simultaneously with the Brownian motion of the bead. The perturbed motion of the bead is a result of photon momentum transfer from the fluorescence of the dye to the trapped scatterer. The bead position fluctuations indicate the presence of the fluorescence and its bleaching nature. The results demonstrate the capability of the photonic force microscopy technique to be a complement to spectroscopy in the study of optical processes.