Raman Spectroscopy

Raman spectroscopy is an analytical tool that can be done at both at microscopic and macroscopic scales, on solid or liquid samples, and provides information about the chemical composition and mechanical properties of samples. What kind of samples? Oh so many! It has traditionally been used for pharmaceuticals, silicon wafers and mineorology but the possibilities are really broad.

Figure 1. Raman spectrum of polystyrene. Each of the peaks corresponds to a molecular feature and together they tell a unique story for each sample. ©Lever Photonics.

How does it work?

We shine a laser to the sample, the light then interacts with the molecules in it and because of those interactions, some of the photons change. When we collect many, many photons, what we see are peaks that 1) tell us to how much the photons energy changed compared to what it was before the interaction (x-axis), and 2) how many of the photonics changed (y-axis).

Together all the peaks form a spectrum, think of it as a histogram of the number of photons changed at each different energy. Each spectrum is a unique fingerprint for each sample, and it is packed with information that without good matematical tools would be too hard to interpret, even for the experts.

For a more complete explanation of Raman scattering, we recommend it's Wiki's page.

Raman scattering as an spectroscopy and imaging tool

Since each molecule's Raman spectrum is unique, like a fingerprint, it can be used to do all sorts of identification, whether it is for verification, authenticity, or impurities analysis. Raman scattering is also proportional to the concentration of molecules in the sample, making it a really powerful quantitative tool, that is, it can determine relative concetrations and in some instances absolute concentrations of the molecules in a given sample.

When the sample is a solution or a blend, in other words homogeneous, we often get the information needed from only one spectrum. For example, from Figure 1. we know that sample is 100% polystyrene. On the other hand, when the sample is not uniform, Raman spectra collected on different spots on the sample can be used to reconstruct a map based on the Raman fingerprint of each different component. Figure 2 shows a Raman image of a cheek cell (thanks Maria for the cell!) showing where lipids are. Where it is dark there is water, and where it is bright there are lipids.

Figure 2. Raman map of a cheek cell reconstructed based on one of the features in the spectra that corresponds to lipids. Brighter means more lipids. ©Lever Photonics.

Applications of Raman Spectroscopy

Here is where it all starts to make sense (hopefully). We will go you through some examples of what Raman spectroscopy can do, but it is truly not practical to go through every possible example. Please contact us or book a time with us if you have any questions about Raman or you'd like to discuss a particular application.

Hopefully these examples will give you a good idea of Raman's super-powers, so you will have a better idea of what questions to ask, but if not, we would love your feedback on how to make this site btter!

We couldn't wait to share the website with you! We are finishing writing the applications of Raman as you read this!

  • Polymers

  • Suppl.

  • Pharma

  • Minerals

  • Semi

  • Food

  • Carbon

  • Meta

  • Biomedical