Confocal Fluorescence Microscope Studies of the Adsorptive Behavior of Dioctadecyl-rhodamine B Molecules at a Cyclohexane-Water Interface

The capabilities of using a confocal fluorescence microscope (CFM) for the interface-selective observation of dye molecules at an oil-water interface were evaluated. A simple expression for a criterion of interface selectivity was derived. The adsorptive behavior of dioctadecyl-rhodamine B at a cyclohexane-water interface was investigated experimentally to demonstrate the interface-selective observation with a CFM. The minimum number of detectable molecules in the probe area at the interface was estimated to be 82 for the present system. Preliminary experimental results of co-adsorption systems composed of adsorbed dye molecules and charged surfactants are also presented.