|
A large variety of spectroscopic techniques are available for the analysis of materials and chemicals. Among these is Raman spectroscopy. This relies on Raman scattering of light by a material, where the light is scattered inelastically as opposed to the more prominent elastic Rayleigh scattering. This inelastic scattering causes shifts in wavelength, which can then be used to deduce information about the substance. Properties of the substance can be determined by analysis of the spectrum, and/or it may be compared with a library of known spectra to identify a substance.
|
Advantages
- Can be used with solids, liquids or gases.
- No sample preparation needed.
- Non-destructive
- No vacuum needed unlike some techniques, which saves on expensive vacuum equipment.
- Short time scale. Raman spectra can be acquired quickly.
- Can work with aqueous solutions (infrared spectroscopy has trouble with aqueous solutions because the water interferes strongly with the wavelengths used)
- Glass vials can be used (unlike in infrared spectroscopy, where the glass causes interference)
- Can use down fibre optic cables for remote sampling.
|
Disadvantages
- Cannot be used for metals or alloys.
- The Raman effect is very weak, which leads to low sensitivity, making it difficult to measure low concentrations of a substance. This can be countered by using one of the alternative techniques (e.g. Resonance Raman) which increases the effect.
- Can be swamped by fluorescence from some materials.
|
