Source : http://www.jkwchui.com
As noted in a previous chapter, the light our eyes see is but a small part of a broad spectrum of electromagnetic radiation. On the immediate high energy side of the visible spectrum lies the ultraviolet, and on the low energy side is the infrared. The portion of the infrared region most useful for analysis of organic compounds is not immediately adjacent to the visible spectrum, but is that having a wavelength range from 2,500 to 16,000 nm, with a corresponding frequency range from 1.9*1013 to 1.2*1014 Hz.
This exercise is intended to familiarize you with the identification of functional groups in organic compounds using infrared spectra. Before you can use this technique, you need to have an introduction to infrared spectroscopy and to what an IR spectrum is.
Infrared spectroscopy deals with the interaction of infrared light with matter. The energy of an infrared photon can be calculated using the Planck energy relation.