After completing this unit the student will be able to:
- Describe the selection rule for infrared-active transitions.
- Determine the vibrations for a triatomic molecule and identify whether they are infrared-active.
- Draw the design of a non-dispersive infrared spectrophotometer and describe how it functions.
- Describe the difference between time and frequency domain spectra.
- Explain how a Michelson Interferometer can be used to obtain a time domain spectrum.
- Explain the advantages of Fourier Transform infrared spectroscopy over conventional infrared spectroscopy.
- 4.1: Introduction to Infrared Spectroscopy
- Infrared radiation is the proper energy to excite vibrations in molecules. The IR spectrum consists of near (4,000-12,800 cm-1), mid (200-4,000 cm-1) and far (10-200 cm-1) regions. The mid-IR region is most commonly used for analysis purposes. Vibrational excitations correspond to changes in the internuclear distances within molecules. You have likely recorded infrared spectra in your organic chemistry course.