AES and XPS investigations of molybdenum-sulfur-iodine-based nanowire-type material

Nanowire-type materials produced by single-step synthesis were investigated by XPS and HR AES. A sufficient quantity of these materials was produced for the XPS analyses. AES analyses at selected spots or along selected lines on the surface of the bundles of the material were also performed. HR AES measurements on bundles of different thicknesses were performed and compared. All the types of spectroscopy measurements were quantified, especially with respect to the Mo, S, and I. The Mo : S : I stoichiometries thus determined, deviated from the nominal value. It was also found that the stoichiometry is approximately constant along an individual nanowire bundle, but less so from one bundle to another. However, it was not possible to show conclusively that the diameter of the bundle influences the stoichiometry. The stoichiometry obtained from XPS measurements differs significantly from the one obtained from the AES measurement as well as from the nominal one. A possible explanation for the differences in the stoichiometries measured by AES, XPS, and the nominal values is the influence of the AES analysis on the sample and the interaction between the characteristics of XPS technique and the sample structure. Copyright (C) 2008 John Wiley & Sons, Ltd.