A rhodamine and a cyanine dye on the water surface as studied by laser induced fluorescence microscopy

The properties and behavior of cyanine and rhodamine dyes on the water surf ace were investigated using a laser-induced fluorescence microscope. The ba nd peaks of the absorption and fluorescence spectra and their Stokes shift of the rhodamine dye on the water surface indicated that the polarity on th e water surface is lower than that of bulk water. The rhodamine and cyanine dye molecules formed domains on the water surface. Although RhC18 formed n o aggregate on the water surface below Gamma = 0.7, DiD aggregated signific antly even at Gamma = 0.2 and showed two kinds of domains on the water surf ace. DiD, however, did not aggregate in the LB film below Gamma = 0.7 and s howed aggregation only at multilayers. (C) 2000 Elsevier Science B.V. All r ights reserved.