This is the raman spectra of Toluene I obtained while working at my lab using a raman spectrometer with laser of 532 nm wavelength. Well, I am a physics student, but I want to know how information about vibrational modes and functional groups are inferred from the raman spectra, let's say from this spectra of Toluene. It would be of great help, since I am very curious about this spectroscopy method. I know physics part of raman spectroscopy, but really struggling with its application part.
Answer
Chemists have tables and tables and tables that correlate functional groups to numbers.
For example: http://www2.ups.edu/faculty/hanson/Spectroscopy/IR/IRfrequencies.html
If we see a number on the graph, a certain type of functional group may be present. The sharp one at 3056 tells me aromatic hydrogen. The 2919 is the benzylic hyrodgens. Since I'm a synthesis guy, knowing the exact types of vibrations occurring there was never important to me.
Be warned, chasing every peak is normally quite frustrating. Vastly more important is normally the overall look for comparison with a known compound, which is sort of a molecular finger print.
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