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A poly-epoxy surface explored by Hartree-Fock ΔSCF simulations of C1s XPS spectra

Gavrielides, Andreas and Duguet, Thomas and Esvan, Jérôme and Lacaze-Dufaure, Corinne and Bagus, Paul S. A poly-epoxy surface explored by Hartree-Fock ΔSCF simulations of C1s XPS spectra. (2016) Journal of Chemical Physics, 145 (7). 074703-1. ISSN 0021-9606

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Official URL: http://dx.doi.org/10.1063/1.4960762

Abstract

Whereas poly-epoxy polymers represent a class of materials with a wide range of applications, the structural disorder makes them difficult to model. In the present work, we use good experimental model samples in the sense that they are pure, fully polymerized, flat and smooth, defect-free, and suitable for ultrahigh vacuum x-ray photoelectron spectroscopy, XPS, experiments. In parallel, we perform Hartree-Fock, HF, calculations of the binding energies, BEs, of the C1s electrons in a model molecule composed of the two constituents of the poly-epoxy sample. These C1s BEs were determined using the HF ΔSCF method, which is known to yield accurate values, especially for the shifts of the BEs, ΔBEs. We demonstrate the benefits of combining rigorous theory with careful XPS measurements in order to obtain correct assignments of the C1s XPS spectra of the polymer sample. Both the relative binding energies—by the ΔSCF method—and relative intensities—in the sudden approximation, SA, are calculated. It results in an excellent match with the experimental spectra. We are able to identify 9 different chemical environments under the C1s peak, where an exclusively experimental work would have found only 3 contributions. In addition, we observe that some contributions are localized at discrete binding energies, whereas others allow a much wider range because of the variation of their second neighbor bound polarization. Therefore, HF-ΔSCF simulations significantly increase the spectral resolution of XPS and thus offer a new avenue for the exploration of the surface of polymers.

Item Type:Article
Additional Information:Thanks to AIP Publishing editor. The definitive version is available at https://publishing.aip.org/ The original PDF of the article can be found at Journal of Chemical Physics website : http://scitation.aip.org/content/aip/journal/jcp
HAL Id:hal-01374287
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > University of North Texas - UNT (USA)
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Agence Nationale de la Recherche
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Deposited By: Diane SAMELOR
Deposited On:30 Sep 2016 09:10

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