Abstract

Numerous atomic, molecular, and free radical species play important roles in the photochemistry of the stratosphere, affecting the stratospheric ozone layer, the temperature profile, and as a consequence modifying the transfer of radiation to and from the surface. Nearly all of these molecular and free radical species possess active infrared absorption bands which can be used for identification and measurement, at wavelengths which can penetrate long stratospheric paths without being absorbed by the major stratospheric constituents, such as ozone. Since it is not uncommon for these species to exist at mixing ratios of parts-per-billion, high sensitivity, long path absorption techniques are employed. Due to the low ambient pressure environment, the absorption lines of these species in the mid- and far-infrared are narrow, with halfwidths ranging from about 10⁻³ cm⁻¹ to 10⁻² cm⁻¹. The ability of high resolution infrared laser techniques to resolve these lines provides the possibility of increased sensitivity and accuracy, which justifies the investment in high resolution IR spectroscopy and in new instrument development.

© 1983 Optical Society of America