Introduction to Infrared & Terahertz Spectroscopy Infrared (IR) and Terahertz (THz) spectroscopy are powerful analytical tools that measure the absorption of light in the IR or THz portion of the electromagnetic spectrum. IR spectroscopy measures the absorption of light in the mid-infrared range, while THz spectroscopy measures the absorption of light in the far-infrared range. IR and THz spectroscopy can be used to identify, quantify, and characterize chemical compounds. IR spectroscopy works...