In this chapter we will focus on the methods for chemists to determine the structure of organic compounds. As part of the efforts for scientists to searching for new compounds for medical, material or new energy resource purpose, determining the structures of the new compounds is a very critical step. A number of instrumental spectroscopy techniques have been used broadly for such purpose. Spectroscopy is the study of the interaction of matter and electromagnetic radiation, and how these interactions can be quantified, analyzed and interpreted to gain information about the structure of matter. For the purpose to identify the structures of organic compounds, we will specifically study how molecules interact with electromagnetic radiation, so the spectroscopy techniques in our discussions here can also be called molecular spectroscopy.
Specifically, we will have discussions about infrared (IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy in this Chapter. IR spectroscopy is a technique applied widely in organic chemistry to detect the presence or absence of a certain functional group, and NMR spectroscopy is the powerful analytical technique that is able to determine the bonding arrangement, or the structure, of a molecule.