| AVS 61st International Symposium & Exhibition | |
| Applied Surface Science | Monday Sessions |
| Session AS+MC-MoM |
| Session: | Quantitative Surface Analysis |
| Presenter: | M. Bravo-Sanchez, CINVESTAV-Queretaro, Mexico |
| Authors: | M. Bravo-Sanchez, CINVESTAV-Queretaro, Mexico J.A. Huerta-Ruelas, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Mexico A. Herrera-Gomez, CINVESTAV-Queretaro, Mexico M.O. Vazquez-Lepe, Universidad de Guadalajara, Mexico F. Espinosa-Magaña, CIMAV-Unidad Chihuahua, Mexico |
| Correspondent: | Click to Email |
Within the transition metal oxides, Fe oxides are among the most technologically relevant. Surfaces analysis through techniques such as X-ray photoelectron spectroscopy (XPS) plays a crucial role in the development of new applications. Despite that a considerable effort has been made on Fe oxides with XPS, many questions are still unanswered mainly due to the lack of a simple and standardized method to adequately model the spectrum of the Fe 2p core level. Complex characteristics such as a steeply background, shake-up satellites, and an asymmetrical line-shape, have been the principal obstacle to obtain accurate areas for proper quantification. In this work, this problem has been confronted by employing the SVSC background [1] and the double Lorentzian line shape [2]. The latter has many advantages over the traditionally employed Doniach-Sunjic line shape, since it is integrable and, then, suitable for quantitative studies.
With this combination of methods it has been possible to closely model the entire Fe 2p spectra (including both the 3/2 and 1/2 branches), which implied accounting for the shake-up satellite already known and the inclusion of a second satellite rarely reported in the literature. A proper determination of areas for accurate quantification of composition and thickness has been achieved taking into account this second satellite located around 725 eV (binding energy), hidden under the 1/2 branch of the main oxide peak. The inclusion of this second signal, together with the already known satellite, improves notably the quantitative analysis of the Fe oxides spectra. The position of the satellites shows a clear dependence on the oxide thickness. Thickness assessment has been confirmed with high-resolution transmission electron microscopy.
[1] A. Herrera-Gomez, M. Bravo-Sanchez, O. Ceballos-Sanchez, and M.O. Vazquez-Lepe. Journal of Electron Spectroscopy and Related Phenomena (in press) DOI 10.1002/sia.5453.
[2] A. Herrera-Gomez. “A double Lorentzian shape for asymmetric photoelectron peaks.” Internal Report. Cinvestav-Querétaro.(2011). http://www.qro.cinvestav.mx/~aherrera/reportesInternos/doubleLorentzian.pdf