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

 

Introduction:
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 FT-IR 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 FT-IR that is just as quick and efficient. 

 

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