Polarization Effects in Fluorescence Emission Spectra from Microdroplets
S.Arnold, N.L.Goddard, and S.C.Hill
J. Chem. Phys. 111, 10407-10411(1999)
We report a pronounced nonclassical polarization effect on the shape of fluorescence emission spectra from an isolated microdroplet coated with a dilute layer of surfactant molecules. The shape of the spectrum measured at 90o is sensitive to the orientation of the analyzer. We measure the largest difference in spectral shape for 90o scattering with the incident polarization directed toward the detector. Imaging reveals that the sources of the emission principally arise from two distinct regions near the surface of the droplet which are diametrically opposed and along the axis of the incident laser beam. The effect appears to be the direct result of coupling between molecular emission moments and electromagnetic modes of the droplet. It is not the molecule which radiates but the molecule-microvessel. Directional emission is sensitive to the polarization of the electromagnetic mode which is stimulated by the coupling.