When should I use Raman spectroscopy?

Raman spectroscopy is a powerful technique which can have many advantages over other common analytical techniques, depending on the purpose of the analysis.  The following points highlight the key Raman advantages:

  • Detailed chemical/molecular analysis
    Raman spectroscopy offers very detailed sample characterisation by probing individual chemical bond vibrations.  As a result, a Raman spectrum is information rich, and contains data relating to the specific chemical structure of the material being analysed.  It can be used to fully characterise a material’s composition, and fast identification of unknown materials is possible with the use of extensive Raman spectral databases.
  • Subtle information (crystallinity, polymorphism, phase)
    Beyond general material identification and characterisation, Raman spectroscopy also probes more subtle chemical effects, such as crystallinity, polymorphism, phase, intrinsic stress/strain, protein folding and hydrogen bonding.
  • Speed
    Raman spectroscopy is a very fast technique, typically requiring just a few seconds to obtain a good quality spectrum.  No sample preparation is required, so sample throughput is high.
  • No sample preparation
    Unlike many analytical techniques which require sample preparation (such as dissolution, grinding, glass formation, or pressing) in order to achieve results, Raman analysis can be made on ‘as received’ samples with no preparation.  This is true whether a sample is a solid, liquid, powder, slurry or gas.
  • Non-destructive
    Raman spectroscopy is a completely non-destructive technique – it is non-contact, non-destructive, and requires no sample preparation.  Thus it is possible to analyse samples such as historic pigments or vital forensic evidence, and retain the sample for additional analysis by other techniques if necessary.
  • Microscopic spatial resolution
    When performed using a confocal Raman microscope, Raman spectroscopy offers the analyst high sensitivity microscopic analysis with sub-micron spatial resolutions.  Thus, individual grains and particles, and specific regions of a sample can be analysed.  Raman micro-spectroscopy retains all of the above advantages.
  • Confocal analysis
    A true confocal Raman microscope provides full 3D spatial resolution, allowing analysis of a discrete volume in a transparent sample.  This property is particularly useful for analysis of layered samples (such as polymer laminates), inclusions (such as those found in glass and minerals), thin samples on a substrate (such as cells and tissue on a microscope slide) and materials in glass/plastic containers (such as a liquid in a bottle).
  • Suitable for in situ, in vitro and in vivo analysis
    Since Raman spectroscopy is a non-contact and non-destructive technique, it is suitable for true in situ analysis.  It can be used to probe chemical reactions within a reaction vessel, without perturbing the reaction in any way.  The tolerance of Raman spectroscopy to water additionally allows it to be used for in vitro and in vivo analyses – examples include the analysis of cosmetics on skin, single cell characterisation for microbiology, and drug-cell interactions for intelligent drug design.

If your analysis requires (or would benefit from) any of the above, then it is likely that Raman spectroscopy could be useful for you.

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