Learning Objectives:
   1. Determine the benefits of Raman and IR spectroscopies
   2. Analyze similar compounds with vibrational spectroscopies

 

Background:
Chemists use a variety of instruments to either verify that they have synthesized a compound as intended or to simply characterize an unknown substance (i.e. determine its identity). The most common instruments used for characterization are GC, MS, 1H and 13C FT-NMR spectroscopy, and FTIR spectroscopy. GC and MS give valuable insight into a compound's size and polarity. NMR spectroscopy can help to determine the functional groups present on a molecule as well as the number of unique protons and carbons it contains and their local environments. Both techniques also reveal invaluable information about the substance's purity. FTIR is a quick, non-destructive method for identifying the functional groups and types of bonds present in a molecule. It is often the first technique employed in the investigation of a substance's identity because of how fast it can be done and how easy it is to interpret the resulting spectra.

 

Another technique that gives similar information to FTIR spectra but has different strengths in certain instances is Raman spectroscopy. Raman spectroscopy is a technique that has existed for almost a century. Initially, it was rarely used as it required extensive instrument and sample preparation and took a very long time. However, recent advances of technology have brought the technique to the forefront of chemistry it is as a complementary characterization tool to FTIR that is just as quick and efficient. 

 

In this lab, you will be introduced to the power of FTIR and Raman spectroscopy, or as they are collectively known, 'vibrational spectroscopies'.