Application of chemometrics to electron spectra

Motivation and results

Modern spectrometers - and this is not restricted to electron spectrometers - will not produce only a single spectrum but whole sets of spectra obtained at different locations (line scans, images), depths (sputter or angle resolved depth profiles), and/or at differently treated samples. These data sets can contain a huge amount of information. Besides the evident information (i.e. prominent peaks for element identification and concentration calculations) much more information can be gained from the data by mathematical methods.

In our research work we were led to the application of chemometrical methods, especially factor analysis, in electron spectrometry (AES, XPS) with the aim to extract the maximum amount of information from the collected spectroscopic data.

We have demonstrated the efforts of these methods at a widespread of applications especially in the fields of thin film and surface analysis [1-7]. The routines have also applied to electron loss spectra in the TEM [8].

We developed a Matlab® based package of routines for factor analysis of electron spectra (AES, XPS, EELS). The routines does not require a special data format. Download of a manual is possible here (hitherto German version only: Handbuch Deutsch).

 

References

  1. S. Baunack, S. Oswald, "Application of factor analysis in electron spectrometry (AES, XPS) for material science", Zeitschrift f. Metallkunde 96 [9] (2005) 972-982.
  2. R. Reiche, S. Oswald, K. Wetzig, "XPS and factor analysis for investigation of sputter-cleaned surfaces of metal (Re, Ir; Cr)-silicon thin films” Appl. Surf. Sci. 179 (2001) 316-323.
  3. S. Baunack, "Data Preprocessing in Peak Shape Analysis of Auger Electron Spectra", Mikrochim. Acta 133 [1-4] (2000) 307-312
  4. R. Reiche, S. Oswald, D. Hofman, J. Thomas, K. Wetzig, "Bombardment-induced silicide formation at rhenium-silicon interfaces studied by XPS and TEM”, Fresen. J. Anal. Chem. 365 (1999) 76-82.
  5. S. Baunack, S. Oswald, D. Scharnweber, "Depth distribution and bonding states of phosphorus implanted in titanium investigated by AES, XPS and SIMS", Surf. Interface Anal. 26 (1998) 471-479.
  6. S. Oswald, S. Baunack, "Application of XPS and factor analysis for non-conduction materials", Surf. Interface Anal. 25 (1997) 942-947.
  7. S. Baunack, S. Kúdela, A. John, V. Liebich, "Application of chemometrical methods in Auger electron microanalysis of composites", Fresenius J. Anal. Chem. 355 (1996) 633-637.
  8. J. Thomas, H.-D. Bauer, S. Baunack, K. Wetzig, "Investigations on Nanoscale Multilayers by Analytical TEM in Scanning Mode", Cryst. Res. Technol. 35 (2000) 839-849.