MEASUREMENT OF THE ABSORPTION-COEFFICIENT OF GASES WITH INTEGRATING SPHERES

For measuring small gas concentrations by means of the absorption spec troscopy a sufficiently long optical path is required. This can be adv antageously realized by multiple diffuse reflections within a suitable integrating sphere. In comparison to the actually used long path cell s integrating spheres have a considerably smaller volume/optical path- ratio. The theory proves that the absorption coefficient of the gas ca ll be estimated by measuring the stationary wall irradiance as well a by measuring the decay constant of the wall irradiance.