Mid-infrared
spectroscopy (MIR) is a vibrational spectroscopy technique that identifies
chemicals based on the interaction of molecules with electromagnetic radiation
in the mid-infrared region (400-4000 cm-1). Infrared
spectroscopy identifies chemicals based on the absorption of specific
wavelengths of mid-infrared light by a molecule. Molecular absorbances of
mid-infrared light cause molecular rotations and vibrations and are classified
by chemical functional groups. The resulting MIR spectrum produced is
characteristic for a given molecule. Attenuated total reflection (ATR-MIR) is
the most popular sampling technique used in most laboratories today, and allows
for the fast analysis of solid and liquid materials. MIR spectra can be
searched against large reference spectral databases, making this technique a
powerful tool for identification of chemical unknowns.
Instruments are
available in a variety of form factors.
The most common are benchtop instruments, but a growing number of
manufacturers have released portable and handheld models. The technique is mature with a large number
of companies having MIR instruments on the market. There is a wide range of prices depending on
form factor and other capabilities.
Typical cost is on the order of $20,000-$100,000.