FTIR measures the absorption caused by infrared active molecules. This technique involves generation of a light beam over a range of wavelengths in the near-IR portion of the spectrum. The beam passes through a parcel of atmosphere in which chemical species absorb IR radiation at characteristic wavelengths. The beam is reflected directly back on itself to the receiver/transmitter. The received spectrum is compared to a library spectrum for each chemical compound of interest so that the compounds present can be identified and qualified. Data analysis is conducted using a PC and a software package. www.aboutremediation.com