Structural Change of Surfactants in Forming of Metal Colloids in the Emulsions

+in the reverse micelles of various surfactants in oil/water systems, and to pursue the change of solvation structure in the photo-reduction process of AgBr. In this report, we demonstrate the result of EXAFS analysis for the solvation structure of Br in the reverse micellar systems. Experimental NaBr solutions (455 mM) were composed of 9.0 vol% distilled water, 45.5 vol% petroleum solvent (main compounds: paraffin > 90%, naphthen < 10%), and 45.5 vol% cationic surfactant (A - C), as shown in Table 1. Other Br (333 mM) solutions dissolving more than two kinds of surfactants were composed of 8.3 vol% distilled water, 41.7 vol% petroleum solvent, and 50 vol% surfactants. These solutions contained both Br and surfactants [cationic surfactant (A), nonionic surfactant, and DTAB (or TBAB)], as shown in Table 1. The volume ratio of cationic to nonionic surfactant was 5 to 1. All the surfactants were kindly provided from Nikka Co. Ltd. Those samples were then poured into cells for EXAFS measurements. Br-K edge EXAFS spectra were collected at the BL-7C and/or BL-10B. The EXAFS measurements were carried out at room temperature in a transmission mode to estimate the coordination numbers around Br in the water domain in the reverse micellar systems.