Knowledge Bank

The importance of molecular free radicals in understanding atmospheric chemistry has motivated the development and application of numerous techniques to detect and quantitatively measure such species, both in the atmosphere and the laboratory. This report will focus on the use of a Fourier transform spectrometer coupled to a fast flow multipass absorption cell to observe vibrational transitions of transient atmospheric species. Laboratory results will be presented for $C10,FO,HO2,DO2,SO,CS$, and other free radicals. The feasibility of this technique is determined mainly by two factors: 1) the ability to generate high concentrations of free radicals, and 2) instrumental considerations relating to the fundamental limitations of the apparatus such as detectors and continuum sources. Both of these considerations will be discussed in relation to our results.