Midinfrapunaa

Midinfrapunaa, or mid-infrared radiation, refers to the portion of the electromagnetic spectrum with wavelengths roughly between 2.5 and 25 micrometers. In Finnish usage the term denotes this spectral region, which lies between near-infrared and far-infrared. Photons in this range carry energies around 0.05–0.5 eV, depending on wavelength, and are not visible to the human eye but interact strongly with molecular vibrations.

The midinfrapunaa region is especially important in spectroscopy because many chemical bonds exhibit characteristic absorption bands here. The so-called fingerprint region, roughly 6–15 μm, contains numerous bands that help identify and quantify organic and inorganic compounds. Because of these features, MIR spectroscopy is widely used in chemistry, materials science, and environmental sensing.

Generation and detection of midinfrapunaa light rely on specialized sources and detectors. Common sources include thermal emitters, as well as laser systems such as quantum cascade lasers and optical parametric oscillators that provide tunable MIR light. Detectors often use materials like mercury cadmium telluride (HgCdTe, MCT), indium antimonide (InSb), or PbSe, many of which require cooling to reduce noise. Suitable optical components include zinc selenide (ZnSe) and calcium fluoride (CaF2), and MIR instruments are widespread in laboratories, industry, and astronomical instruments.

Applications span chemical analysis, atmospheric monitoring, pharmaceuticals, and astronomy. MIR imaging and spectroscopy enable non-destructive analysis of materials, detection of trace gases, and observation of warm astronomical objects. Limitations include significant atmospheric absorption and the need for specialized detectors, but ongoing advances aim to improve sensitivity, portability, and operating temperature.