How does infrared spectroscopy work and where might you see it used in real life?

Infrared radiation has a longer wavelength than visible light, and is also called thermal radiation. The chemical bonds in molecules absorb infrared radiation at characteristic frequencies, which means it can be used to identify what bonds are present. The right-hand region of the spectrum is called the "fingerprint region", which contains many absorptions due to bending vibrations of molecules. This is called the fingerprint region because it will differ between molecules that are very similar in structure, allowing them to be differentiated.

Infrared spectroscopy might be used in airport security. Spectra could be taken from samples and then compared to a database of known compounds, allowing quick identification of explosives or drugs.