Emission spectra of pendant droplets containing dye solutions and emulsions

Fluorescence emission of solutions of Rhodamine 6G (Rh6G) in pendant droplets in distilled water is measured as well as of emulsions of Rh6G in water and Oily Vitamin A. The excitation is made with the second harmonic beam emitted by a pulsed Nd:YAG laser system at 532 nm. Emission spectra measured for pendant droplets containing Rh6G water solution show besides broadband fluorescence an additional peak attributed to lasing effect. For pendant droplet containing emulsion is obtained an enhanced fluorescence with respect to measurements made in bulk or in droplets which contain solutions (not emulsions) of Rh6G in ultrapure water. The results can be useful in optical imaging, since they can lead to the use of smaller quantities of fluorescent dyes to obtain the same quality of results. By increasing pumping energy a narrow lasing line is also obtained in this case. In both systems, the peak wavelength of lasing signal depends on droplet content. This can lead to generation of tunable microlasers that may be used in medical/technologic applications. Acknowledgements: project funding by PN0930/2009, POSDRU/159/1.5/S/137750.