18.3: Applications of Raman Spectroscopy
- Page ID
- 386422
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Raman spectroscopy is useful for both qualitative and quantitative analyses, examples of which are provided in this section.
Qualitative Applications
There are numerous databases that provide reference spectra for inorganic compounds, for minerals, for synthetic organic pigments, for natural and synthetic inorganic and organic pigments, and for carbohydrates. Such data bases are often searchable by not only name and formula, but by the prominent Raman scattering lines. Examples of spectra are included here using data from the databases linked to above.
Quantitative Applications
The intensity of Raman scattering, \(I(\nu)_R\), is directly proportional to the intensity of the source radiation, \(I_l\), and the concentration of the scattering species, \(C\). The direct proportionality between \(I(\nu)_R\) and \(I_l\) is important given that each photon experiencing Raman scattering requires approximately \(10^8\) excitation photons. Using a laser as a source of radiation and increasing its power leads to an improvement in sensitivity. The direct proportionality between \(I(\nu)_R\) and the concentration of the scattering species means that a calibration curve of band intensity (or band area) is a linear function of concentration, allowing for a quantitative analysis.