By means of an optical trapping technique we have been able to trap single microdroplets in emulsions and to observe their Raman and/or fluorescence spectra. In the fluorescence spectra we could observe additional morphology-dependent electromagnetic resonances, from which the radius of the sphere can be determined.
M. Lankers, J. Popp, and W. Kiefer, "Raman and Fluorescence Spectra of Single Optically Trapped Microdroplets in Emulsions," Appl. Spectrosc. 48, 1166-1168 (1994)