Terahertz Technology – Properties of Terahertz Radiation
Properties of Terahertz Radiation
- Frequency range 100 GHz .. 10 THz, wavelengths 3 mm .. 30 µm
- Also known as far-infrared or sub-millimeter waves
- Non-ionizing, but penetrates clothing, paper, cardboard, plastics, …
- Absorbed by water and many organic substances
- High chemical sensitivity
The terahertz range refers to electromagnetic waves with frequencies between 100 GHz and 10 THz, or wavelengths between 3 mm and 30 μm. Light between radio waves and infrared has some unique properties. Terahertz waves pass through a variety of amorphous substances – many synthetics and textiles, but also paper and cardboard are transparent to terahertz waves. Many biomolecules, proteins, explosives or narcotics also feature characteristic absorption lines, so-called spectral “fingerprints”, at frequencies between 0.1 and 5 THz. The two main advantages of terahertz radiation are thus the penetration of conventionally opaque materials on one hand, and a high chemical selectivity on the other hand.
One of the strongest absorbers for terahertz radiation is water, which – depending on the application – turns out to be a blessing or a curse: Air moisture limits the propagation of terahertz rays to a few meters, but vice versa, the characteristic fingerprint enables a high precision in humidity-sensitive measurements. Liquid water is an even more dominant absorber than water vapor.
Unlike X-rays, terahertz waves do not have any ionizing effects and are generally considered biologically innocuous.