IR spectroscopy is used on a vast scale in industry and research for chemical analyses.
The novelty is its use for measuring the age of wood. The molecules present in wood absorb the IR rays emitted by spectrophotometer if they oscillate at the same frequency. The spectrum showing this absorption with peaks and valleys, is like a fingerprint of the substance under examination. Change undergone molecules or group of molecules, owing, for example, to aging is show up by a displacement of frequencies and by an alteration in the absorption intensities. The age of wood is established comparing these changes to spectra of certain dating.
For more info: Laboratorio Scientifico del Museo D’Arte E Scienza, Milano,Italy