Spectral fluctuation and heterogeneous distribution of porphine on a watersurface

Using a confocal fluorescence microscope, we found a significant temporal f luctuation in the fluorescence spectrum of porphine molecules on the water surface. The spectra fluctuated when the accumulation time was 300 ms and t he pH was within a certain range. No fluctuation was observed with a longer accumulation time (36 s) or on a solid surface. The present observation in dicates that the distribution of porphine on the water surface is heterogen eous and that the Brownian motion of the surface species induces spectral f luctuation. A neutral form of porphine produces domains at a higher surface coverage.