Terahertz radiation has excellent potential to help with the understanding of fundamental and exciting new challenges at the interface between physics, materials chemistry and the life sciences but it is, as yet, largely unexplored. Light located in this range of the electromagnetic spectrum was very difficult to generate until quite recently. Since the 1990s new developments in semiconductor physics and femtosecond laser technology have made it possible to provide light at terahertz frequencies (a frequency of 1 THz equals a wavelength of 0.3 mm) in a relatively simple way.
Terahertz radiation has unique properties in that it easily penetrates through most polymeric materials and is therefore an exciting new tool to study such materials, which are often opaque at visible frequencies. As well as being a non-destructive probe of materials, in organic molecular crystals terahertz radiation has the important property that it interacts with vibrational modes that extend across large domains of a crystal lattice. This makes terahertz spectroscopy unique: even though it is possible to excite molecules using a variety of energies it is only through the careful selection of the low energy in the terahertz range that it is possible to selectively excite crystal lattice vibrations and study in a unique way the presence and nature of interactions between molecules.
By using terahertz spectroscopy our group is aiming to understand the physical characteristics of a wide variety of materials spanning the fields of pharmaceuticals, catalysis, biologicals, nanotechnology and non-destructive testing.