UK-China developed radiation source could offer safer alternative to x-rays 

THz radiation is far-infrared electromagnetic radiation that has a frequency between 0.1THz and 10THz (1THz = 10^12Hz), which fits between the mid-infrared and microwave spectra.

Unlike visible light, radiation penetrates materials such as plastic, cardboard, wood and composite materials, and is a promising replacement for X-rays used in imaging and security.

The vibrational and rotational spectral fingerprints of large molecules coincide with the THz band, which makes THz spectroscopy a powerful tool for identifying hazardous substances, such as drugs and explosives.

THz radiation is important for biology and medicine because many biological macromolecules, such as DNA and proteins, have their collective motion at THz frequencies. It can also be used to uncover the intricacies of semiconductors and nanostructures, and therefore are important tools for developing new electro-mechanical devices and solar cells.

Many different methods of generating THz radiation exist, including driving photocurrents in semiconductor antennas, excitation of quantum wells and optical rectification in electro-optic crystals. However, their maximum power is restricted because of damage to the optical materials at high powers. The use of Plasma acceleration to accelerate charged particles has long been viewed as an attractive alternative.