Infrared Absorption Spectroscopy

Abstract

Infrared (IR) absorption spectroscopy is one of the most important analytical techniques available to study different kinds of samples including solids, semisolids, biological materials, films, liquids, solutions, and gases. IR spectroscopy not only uses the so-called infrared absorption, but also other techniques such as the attenuated total reflection method, diffuse reflectance method, reflection-absorption method, photoacoustic spectroscopy, and emission spectroscopy. IR spectroscopy is a technique based on the vibrations of the atoms of a molecule. An infrared spectrum is obtained by passing infrared radiation through a sample and determining what fraction of the incident radiation is absorbed at a particular energy. Fourier transform infrared (FTIR) spectrometry is based on the use of an interferometer. A common FTIR spectrometer consists of a source, an interferometer, a sample holder, and a detector. Transmission spectroscopy is based upon the absorption of infrared radiation at specific wavelengths as it passes through a sample.