What is Raman spectral imaging or Raman spectral mapping?

Raman spectral imaging (or mapping) is a method for generating detailed chemical images based on a sample‚Äôs Raman spectrum.  A complete spectrum is acquired at each and every pixel of the image, and then interrogated to generate false colour images based on material composition and structure:

  • Raman peak intensity yields images of material concentration and distribution
  • Raman peak position yields images of molecular structure and phase, and material stress/strain
  • Raman peak width yields images of crystallinity and phase

A typical experiment uses sequential sample movement and spectrum acquisition, repeated hundreds, thousands or even millions of times, to collect data from the user defined image area.

Raman spectral images can be collected in two and three dimensions, to yield XY images, XZ and YZ slices, and XYZ datacubes.

Raman spectral imaging is an invaluable technique for scientists in many varied fields, since it allows chemical distribution to be viewed which is invisible by standard optical microscopy.

Raman spectral image of a 0.6 x 2.4 mm area of a pharmaceutical tablet, showing the distribution of aspirin (red), paracetamol (green), caffeine (blue) and cellulose (yellow)
Raman spectral image of a 0.6 x 2.4 mm2 area of a pharmaceutical tablet, showing the distribution of aspirin (red), paracetamol (green), caffeine (blue) and cellulose (yellow)
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