Abstract

Gas pollutants in the atmosphere are present always with very low concentration (typically from one molecule per million molecules to one per billion). Many techniques were developed for quantifying such a small number of molecules covering the UV, visible and infrared regions. Most lab or in situ experiments rely on differential absorption which consists in comparing absorption and non-absorption wavelengths (DOAS, far-infrared difference frequency, diode laser experiments and also the LIDAR technique). These experiments have in common that they work on a very narrow spectrum covering one or a few molecular absorption lines.

© 2000 IEEE