ABSTRACT
This chapter explores time-resolved aspects of THz spectroscopy. THz spectroscopy involves generating and detecting subpicosecond far-infrared (IR) pulses with an ultrafast visible or near-IR laser, as has been discussed in previous chapters. THz spectroscopy covers the region from 0.3 to 20 THz (10-600 cm-1), with most of the work being done between 0.5 and 3 THz. When converted to other units, 1 THz is equivalent to 33.3 cm-1 (wave numbers) or 0.004 eV photon energy or 300 µm wave length. For example, the THz region is ideal for probing semiconductors because the frequency range closely matches typical carrier scattering rates of 1012 to 1014 s-1, allowing for more accurate modeling of the photoconductivity data.
