Spectroscopic methods of detecting and measuring minor gases of the atmosphere

Abstract

Most of the gaseous constituents of the atmosphere are present in only very low abundances. Hence methods of detecting and monitoring them need to be sensitive to concentrations in the ppm or ppb range. In this paper the non‐laser spectroscopic techniques are first reviewed. Principal among these are infrared methods, using either long pathlength absorption cells or multiplex (e.g. Fourier transform) spectrometers, or a combination of both. Laser‐based spectroscopic techniques are then reviewed, both for their application to the study of confined samples and for measurements in the open atmosphere. The latter include methods based on the backscattering of pulsed laser beams ("Lidar” methods), having the unique capability to provide concentration data on individual species at remote locations.