Introduction to Infrared Spectroscopy Chapter 16 Instrumental Analysis Definition of Infrared Spectroscopy w The absorption of light, as it passes through a medium, varies linearly with the distance the light travels and with concentration of the absorbing medium. Where a is the absorbance, the Greek lower-case letter epsilon is a characteristic constant for each material at a given wavelength (known as the extinction coefficient or absorption coefficient), c is concentration, and l is the length of the light path, the absorption of light may be expressed by the simple equation a= epsilon times c times l. Infrared Spectroscopy w Infrared spectroscopy is the measurement of the wavelength and intensity of the absorption of mid-infrared light by a sample. Mid-infrared is energetic enough to excite molecular vibrations to higher energy levels. w The wavelength of infrared absorption bands is characteristic of specific ty...
