Abstract: In this work,some derivatives of Rhodamine B,in which a long hydrocarbon chain compound is included,were studied.Their flurorescence behaviors in various surfactant solutions were studied carefully.It was found that the long hydrophobic hydrocarbon chain Rhodamine B is favorable to aggregate to dimers in water solution. and the dimer formed is also favorable to dissociate to monomer of Rhodamine B when the critical concentration of micellar formation of surfactant is arrived.Results indicate that the long chain Rhodamine B usedas a fluorescent probe for determination of the properties of microenvironment is more sensitive than that of other Rhodamine B derivatives.

Key words: Rhodamine B derivatives, surfactants, molecular probe