From HORIBA Scientific:
RAMAN DATA AND ANALYSIS
Raman Spectroscopy for Analysis and Monitoring
The Raman scattering technique is a vibrational molecular spectroscopy which derives from an inelastic light scattering process. With Raman spectroscopy, a laser photon is scattered by a sample molecule and loses ( or gains) energy during the process. The amount of energy lost is seen as a change in energy (wavelength) of the irradiating photon. This energy loss is characteristic for a particular bond in the molecule. Raman can best be thought of as producing a precise spectral fingerprint, unique to a molecule or indeed and individual molecular structure. In this respect it is similar to the more commonly found FT-IR spectroscopy. However, unlike FT-IR, there are a distinct number of advantages when using Raman.
• Raman can be used to analyse aqueous solutions since it does not suffer from the large water absorption effects found with FT techniques.
• The intensity of spectral features in solution is directly proportional to the concentration of the particular species
• Raman spectra are generally robust to temperature changes
• Raman requires little or no sample preparation. It does not need the use of Nujol, or KBr
matrices and is largely unaffected y sample cell materials such as glass.
• The use of a Raman microscope such as the LabRAM provides very high level of spatial
resolution and depth discrimination, not found with the FT methods of analysis
These advantages and its highly specific nature, mean that Raman has become a very powerful tool for analysis and chemical monitoring. Depending upon instrumentation, it is a technique which can be used for the analysis of solids, liquids and solutions and can even provide information on physical characteristics such as crystalline phase and orientation, polymorphic forms, and intrinsic stress.