Medium infrared spectroscopy refers to medium infrared spectroscopy, a frequency region divided into group frequencies (2.5-8μm), and the fingerprint region (8-15.4μm). In the frequency region of groups, the main bands of absorption can be assigned to units of vibration of a molecule, that is, units that only depend to a greater or less degree of the functional group that produces the absorption and not of the structure of the molecule.
Structural influences appear in themselves as shifts of the absorption bands from one compound to another. The (2.5-4.0μm) absorption range is characteristic of H stretch vibrations with mass elements 19 or less.
When coupled with heavier mass, frequencies overlap in the triple bond region. (4.0-5.0μm) The frequencies of double bonds are in the region between (5.0-6.5μm)
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