The absorption and scattering of sunlight by matter is the reason why the sky and seas are blue, why plants are green, why rainbows have their brilliant colors and why sunglasses protect your eyes. Some of these everyday phenomena involve elastic scattering – scattering with no loss of energy of the emitted light. But sometimes the light that is emitted is of a different wavelength because it has lost some of its energy; this is called inelastic scattering. The Raman effect is one form of inelastic scattering of light and is the basis of a powerful form of non-destructive chemical analysis called Raman spectroscopy. By measuring the degree of energy loss of light, the analyst can identify specific chemical bonds in a sample and obtain a chemical fingerprint of the molecules in the sample, thus allowing its identification.
This Essential Knowledge Briefing provides an introduction to Raman microscopy, and includes an overview of the main ways it is used, from preparing samples for analysis to obtaining Raman spectra and maps. The EKB also discusses practical issues that need to be considered when working with Raman microscopy, how to solve potential problems, and concludes by looking forward to potential future developments.