1. Analysis of SiOxCyHz polymeric materials by x-ray absorption spectroscopy: Anomalous behavior of the resonant Si KLL Auger spectra.
- Author
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Barranco, A., Yanguas-Gil, A., Yubero, F., and González-Elipe, A. R.
- Subjects
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SILICONES , *THIN films , *X-rays , *SPECTRUM analysis , *AUGER effect , *PHOTONS , *POLYMERIC composites - Abstract
Silicone-like SiOxCyHz polymeric thin films with different C/O atomic ratios have been studied by x-ray absorption spectroscopy and resonant Auger electron spectroscopy. The energy of the onset of the Si K absorption edge varies with the film composition from the value observed in SiC (i.e.,∼1840 eV) to that in SiO2 (i.e.,∼1844 eV). In the samples with a low C/O atomic ratio (i.e.,∼1),the main band of the Si K spectra depicts two well defined peaks that can be associated with the Si-C and Si-O bonds present in the samples. Their relative intensity can be used to assess the concentration of these two bond types. Resonant Si KLL Auger spectra of the polymeric thin film have been measured using photon energies across the Si K absorption edge. A first Auger peak appearing at a high kinetic energy was recorded for photon energies around the onset of the absorption edge and the first peak/shoulder of the Si K spectrum associated with the Si-C bonds. This resonant Si KLL Auger signal depicts the typical behavior of a resonant Auger process, i.e., its intensity increases when increasing the photon energy, passes through a maximum and then decreases to disappear. In parallel with the evolution of this resonant spectrum, a “normal” Si KLL Auger spectrum with a lower kinetic energy appeared for photon energies around the middle of the absorption curve. This spectrum is the only one prevailing at photon energies well above the absorption edge. An outstanding behavior of the Si KLL resonant Auger peaks in the polymers with a high C/O atomic ratio (i.e., >=4) is that they present a negative dispersion with photon energy, i.e., their kinetic energy decreases as the photon energy increases. This behavior is opposite to that generally found for resonant Auger peaks in most systems and particularly for SiO2. Although the origin of such behavior is still unclear, the study of the Si K absorption edge and the corresponding Si KLL resonant Auger spectra results helpful for the structural and electronic characterization of SiOxCyHz polymers. [ABSTRACT FROM AUTHOR]
- Published
- 2006
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