Cluster analysis of soft X-ray spectromicroscopy data

M. Lerotic*, C. Jacobsen, T. Schäfer, S. Vogt

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

136 Scopus citations

Abstract

Soft X-ray spectromicroscopy provides spectral data on the chemical speciation of light elements at sub-100 nm spatial resolution. When all chemical species in a specimen are known and separately characterized, existing approaches can be used to measure the concentration of each component at each pixel. In other cases (such as often occur in biology or environmental science), some spectral signatures may not be known in advance so other approaches must be used. We describe here an approach that uses principal component analysis to orthogonalize and noise-filter spectromicroscopy data. We then use cluster analysis (a form of unsupervised pattern matching) to classify pixels according to spectral similarity, to extract representative, cluster-averaged spectra with good signal-to-noise ratio, and to obtain gradations of concentration of these representative spectra at each pixel. The method is illustrated with a simulated data set of organic compounds, and a mixture of lutetium in hematite used to understand colloidal transport properties of radionuclides.

Original languageEnglish (US)
Pages (from-to)35-57
Number of pages23
JournalUltramicroscopy
Volume100
Issue number1-2
DOIs
StatePublished - Jul 2004

Keywords

  • 07.05.Kf
  • 07.85.Tt
  • 61.10.Ht
  • 78.70.Dm
  • Cluster analysis
  • Principal component analysis
  • X-ray microscopy
  • X-ray spectromicroscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Instrumentation

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