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Surface structure of cationic surfactant solutions investigated by angular resolved X‐ray photoelectron spectroscopy with calibrated transmission function

The main goal of the present work is to investigate the surface structure of cationic surfactant solutions by angular resolved X‐ray photoelectron spectroscopy (ARXPS) after calibrating transmission function of the spectrometer. We have estimated the transmission function of the ARXPS spectrometer, and with it, we investigated solution of tetrabutylammonium iodide in a nonaqueous polar solvent. By genetic algorithm, the fractional concentration‐depth profiles of constituents were reconstructed. These depth profiles evidence the enrichment of surfactant and the depletion of solvent in the surface regime and verify the separate distributions of oppositely charged surfactant ions. From those profiles we draw a conclusion that there is a preferred orientation for cation present at the surface, and the possibility for cation to take this orientation is related to its surface amount. Copyright © 2010 John Wiley & Sons, Ltd.