In this work the maximum entropy method (MEM) is applied, for the first time, to angle-resolved X-ray photoelectron spectroscopy (ARXPS) data from oxy-hydroxide films on iron surfaces. This nondestructively derives information on the in-depth distribution of the composition and chemical state. An MEM algorithm was created and first tested on the simulated data. The reconstructed composition depth profiles agreed very well with the theoretical ones up to 5% Gaussian noise added to the data. The same algorithm was then applied to ARXPS data from iron samples to investigate the in-depth variations in the composition and chemical state of the nanosized oxy-hydroxide film naturally grown on the iron surface. The resulting surface film presents a complex multilayer structure with concentration gradients. The effect of air exposure on the structure was also investigated.

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Small-angle X-ray (SAXS) scattering and 14 N NMR relaxation were determined for microemulsion samples formed from didodecyl dimethylammonium bromide (DDAB), water, and tetradecane to deduce the associated microstructures. The swelling features within the tetradecane microemulsion are unusual compared with those of DDAB/water/alkane analogues formed with shorter n-alkanes: tetradecane-containing microemulsions do not show the characteristic anti-percolation transition seen for the latter microemulsions. Experimental data along tetradecane dilution lines are consistent with a continuous transition from a bilayer to monolayer structure of the surfactant interface. The evolution is topologically complex. It involves the annealing of bilayer punctures that occur on oil dilution. A quantitative model that allows continuous transformation from multihandled bilayers (typical of L 3 sponge mesophases) to multihandled monolayers (typical of microemulsions modeled with shorter chained alkanes) is proposed that well fits the observed behavior.