Infrared (IR) spectroscopy identifies chemical compounds by measuring their vibrational transitions, which correspond to specific molecular bonds and functional groups.

IR spectroscopy works by passing infrared light through a material and recording which wavelengths are absorbed. These absorptions correspond to vibrations in molecular bonds, such as C-H, O-H, and C=O stretches. Because each functional group has characteristic absorption patterns, IR spectra act as molecular signatures for identification and structural elucidation of organic and some inorganic compounds.