Terahertz spectroscopy

Antony N. Davies provides information regarding some of the factors that need to be considered when using terahertz (THz) spectroscopy. Some top-of-the-range research grade spectrometers could be equipped to operate in the so-called terahertz gap. There are many good reasons for spectroscopists and others to want to explore the capabilities of this region of the electromagnetic spectrum in such spectroscopic instruments. He states that at a simple level the technology development which is capable of revolutionizing this area of spectroscopy revolves around the development of an emitter consisting of an array of photoconductive switches on a Gallium-Arsenide (GaAs) substrate. These commercially available sources of THz radiation function through the stimulation of the semiconductor substrate by the arrival of femtosecond pulses creating optically excited carriers which are then accelerated by an electric field between the switches which give rises to a broad emission spectrum of terahertz frequency radiation.