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Keywords:

  • Raman microscopy;
  • BTEM;
  • curve resolution;
  • pure component spectra;
  • spatial distributions

Abstract

The combined application of Raman microscopy and self-modeling curve resolution techniques can address a wide range of material characterization problems. In particular, the combination of Raman microscopy and the Band-Target Entropy Minimization (BTEM) algorithm has been applied to various organic, inorganic, pharmaceutical and bio-material related problems. In the present contribution, the principles behind this type of analysis are reviewed, followed by a number of case-by-case studies. For each of these examples, a Raman microscopic mapping measurement (consisting of 100 s up to 1000 s of spectra) is performed, followed by BTEM analysis which provides the underlying pure component spectra of the constituents present in the system without the use of any a priori information. In most cases, outstanding signal-to-noise ratios for components at the 0.1-1.0 % level can be obtained, and sometimes trace constituents can also be detected. Subsequently, the identity of the components can be determined by comparison to spectral libraries. Finally, the reconstructed pure component spectra can be further used to obtain the spatial distribution of the constituents present in the sample. Copyright © 2012 John Wiley & Sons, Ltd.