Light not only can be seen other than with the eyes but also through reflecting or scattering with other materials. Spectroscopy studies the absorption and emission of light and other radiation. A substance might only be seen as a blue reflection if other lights on it are completely absorbed.
Raman Spectroscopy is a powerful tool to detect certain interactions of light with matter, a molecular spectroscopic technique utilizing the interaction of light. Using this spectroscopy, you gain insight into what makes up a material or its characteristics.
It uses an analytical technique where scattered light measures the vibrational energy modes of a sample. You can see a tiny fraction of scattered light with a different color using a Raman spectrometer. Raman spectroscopy extracts both chemical and structural information through Raman scattering detection.
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About Raman Scatter
The Raman scattering process is named after its discoverer, the famous Indian physicist C.V. Raman. It is when photons interact with a molecule. During this time, the molecule may advance to a higher energy, a virtual state. The scattering process changes frequency because of the interaction with molecular vibration.
What information does Raman spectroscopy provide?
Raman spectroscopy provides information on both inorganic and organic chemical species. Raman spectroscopy can have information on the chemical structure of a material, including:
- Chemical structure and identity
- Phase and polymorphism
- Intrinsic stress or strain
Raman’s information can be useful in metal compounds with low vibrational absorption frequencies. Not only that, but Raman is also useful for determining functional groups and fingerprints of organic molecules.
A Raman has a spectral library for identifying a material based on its Raman spectrum. This library contains a thousand spectra for finding a match of the spectrum of a certain analyte.
Raman Analysis
In the case of gases, where the concentration of molecules is very low, measuring it is not easy. Using specialized equipment like high-powered lasers and long path-length samples is necessary. But there are also some cases where gas pressures are high, which means Raman instrumentation can be used easily.
Raman analysis for a mixture of materials
The Raman spectrum will contain information about different molecules from a mixture of materials. The peak intensities can generate quantitative information on the mixture’s composition if a mixture of components is known in the spectrum system. The Chemometrics method is used to build quantitative methods if it’s a case of complex matrixes.
What are the types Raman Spectroscopy can analyze?
Since it can even analyze a mixture of materials, Raman can be used in the analysis of the following:
- Solids, powders, liquids, gels, slurries, and gasses
- Inorganic, organic, and biological materials
- Pure chemicals, mixtures, and solutions
- Metallic oxides and corrosion
Conclusion
Raman spectroscopy is a powerful tool using the scattering of light. It also can help with the analyses of solids, liquids, gas, and a mixture of materials. Although there are types unsuitable for analysis, it’s only a little compared to the big amount it can.
References: https://www.renishaw.com/en/a-basic-overview-of-raman-spectroscopy–25805
https://www.horiba.com/rus/scientific/technologies/raman-imaging-and-spectroscopy/raman-spectroscopy/
https://chem.libretexts.org/Bookshelves/Analytical_Chemistry/Physical_Methods_in_Chemistry_and_Nano_Science_(Barron)/04%3A_Chemical_Speciation/4.03%3A_Raman_Spectroscopy
https://www.edinst.com/blog/what-is-raman-spectroscopy/
