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Updated: Jun 23, 2026
08:53
Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures
Published on: October 9, 2012
Determination of the electron escape depth for NEXAFS spectroscopy
K E Sohn1, M D Dimitriou, J Genzer
1Department of Materials, University of California Santa Barbara, Santa Barbara, California 93106, USA.
Langmuir : the ACS Journal of Surfaces and Colloids
|April 30, 2009
Summary
A new method analyzes near-edge X-ray absorption fine structure (NEXAFS) spectra to determine carbon atom density depth profiles. This approach reveals that carbon density in polymer films is not constant, enabling accurate electron escape depth (EED) calculations.
Area of Science:
- Materials Science
- Surface Science
- Spectroscopy
Background:
- Near-edge X-ray absorption fine structure (NEXAFS) is a surface-sensitive technique.
- Accurate analysis of NEXAFS spectra often relies on assumptions about material properties, such as constant atom density.
- The validity of these assumptions, particularly for polymer films, requires investigation.
Purpose of the Study:
- To develop a novel method for determining carbon atom density as a function of depth using NEXAFS.
- To challenge the common assumption of constant carbon atom density in polymer films.
- To calculate the electron escape depth (EED) for NEXAFS and apply it to polymer surface analysis.
Main Methods:
- Analysis of the postedge signal in NEXAFS spectra.
- Development of a depth-dependent carbon atom density determination method.
- Application of the method to a model bilayer system (perfluorinated polyether on highly oriented pyrolitic graphite).
Main Results:
- Demonstrated that carbon atom density is not constant with depth in polymer films.
- Calculated the electron escape depth (EED) for NEXAFS to be 1.95 nm in a model system.
- Successfully measured the thickness of a perfluorinated surface layer using the determined EED.
Conclusions:
- The developed method provides a more accurate analysis of NEXAFS data by accounting for depth-dependent carbon density.
- The calculated EED is crucial for precise surface layer thickness measurements.
- This technique advances the characterization of polymer surfaces and thin films.
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