Raman Spectroscopy

 What is Raman Spectroscopy?
  • Radiation incident upon a molecule can undergo several types of scattering, including:
  • Rayleigh (elastic) scattering where the photon energy remains the same
  • Raman (inelastic) scattering, in which the photon energy can decrease (stokes), or decrease (anti-stokes); the change in energy being stored in (released from) vibrational motion
  • Raman scattering occurs with a much lower probability (~1,000,000,000 times less) than Rayleigh scattering
  • Energy changes are measured as a frequency shift, and reported as wave numbers (inverse centimeters) for convenience 
Why Use Raman Spectroscopy?
  • Information on rotational and vibrational levels
  • Raman effect small but accessible by use of lasers
  • Complementary information to IR spectroscopy p homonuclear diatomic molecules, low frequency range
  • In situ analysis of organic and inorganic compounds
  • Analysis of aqueous solutions and solids (powders)

 Applications:
* Pharmaceuticals, Chemicals, Cosmetics
          Off line & Online monitoring
* Food and food contaminants/additives 
* Counterfeit Identification 
* Natural Products: Tea, Cannabis, Chinese Herbs * Narcotics & intermediates or precursors 
* Content Uniformity Validation 
* Trace material/contaminant testing
*100% Product Quality Assurance  



What is SERS?
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Surface-enhanced Raman spectroscopy or surface-enhanced Raman scattering (SERS) is a surface-sensitive technique that enhances Raman scattering by molecules adsorbed on rough metal surfaces or by nanostructures such as plasmonic-magnetic silica nanotubes.[1] The enhancement factor can be as much as 10x10 to 10x11,[2][3] which means the technique may detect single molecules.[4][5]     (courtesy wikipedia)



SERS vs Standard Raman Sensitivity