THz radiation, also known as terahertz radiation, also travels through space as electromagnetic waves, similar to light. However, THz radiation has a lower frequency and longer wavelength than visible light.
The electromagnetic spectrum spans a wide range of frequencies, from extremely low frequencies (ELF) to gamma rays. THz radiation falls between the microwave and infrared regions of the spectrum, typically ranging from 0.1 to 10 terahertz (10^12 hertz). This places it between the microwave and infrared regions.
Like all electromagnetic waves, THz radiation is generated by the acceleration or oscillation of charged particles, such as electrons. When charged particles are accelerated or undergo certain energy transitions, they emit THz waves.
THz waves can travel through free space and transparent materials, including some non-conductive solids, liquids, and gases. However, they can be absorbed or scattered by certain materials, especially those with high water content, such as biological tissues and some plastics. This absorption and scattering behavior is exploited in various applications of THz radiation, such as imaging and spectroscopy.
THz waves are typically used for their unique properties in terms of sensing and imaging. They can penetrate many common materials that are opaque to visible light, allowing for imaging and detection of concealed objects or structures. Additionally, THz waves can interact with molecular vibrations and rotational transitions, making them useful for spectroscopic analysis and characterization of materials.
In summary, THz radiation travels through space as electromagnetic waves, similar to light. It occupies a specific frequency range in the electromagnetic spectrum and can penetrate certain materials while being absorbed or scattered by others. Its unique properties make it valuable for various applications, including imaging and spectroscopy.