Many materials are partially transparent to infrared light, with different wavelengths of infrared radiation absorbed at different rates.
The identification of unknown compounds can be accomplished by the measurement of the absorption of infrared radiation at different wavelengths, producing an infrared spectrum.
This spectrum is used as a “fingerprint,” and compared to the spectrum obtained from a known material or to libraries of stored spectra of standards to identify the compound present.
Because the infrared absorption spectra of mixtures of materials are often difficult to interpret, sample separation techniques such as solvent extraction may be applied prior to analysis.
To learn more: FTIR Analysis Lab Services