FTIR – Fourier Transform Infrared Spectroscopy.
FTIR uses infrared energy, along with sophisticated instrumentation and software, to detect absorptions in the infrared region of the electromagnetic spectrum. The results are interpreted into digital spectra. A staple in gem testing laboratories, FTIR is one of the more important and complex instruments used in gem testing. It is also one of the more challenging instruments to master and interpret. FTIR can identify the minerals present, but is most important in identifying modern treatments and some of the more sophisticated synthetics. FTIR is utilized to identify hydrothermally grown synthetic crystals, such as emerald and quartzes. It also identifies polymer-treated gem materials such as jades, turquoise, emerald, and any gem that may be clarity enhanced with polymers. It is also used to detect heat treatment in corundum.
While XRF and UV-Vis spectrometers like to look for atoms, FTIR and Raman are on the hunt for the molecules. For an in depth look on how FTIR is used in gem labs and examples of its spectra, please see here.
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