A distributed-feedback (DFB) diode laser radiating at 1.53 μm was used for photoacoustic detection of ammonia molecules in the gas phase under flow conditions. The influence of the adsorption–desorption processes that occur at the cell and tube walls on the measured gas concentration was studied. Dramatic differences in the adsorption behavior of a metal and a polypropylene cell are demonstrated. Simulations of the gas flow and adsorption–desorption processes yield the conditions that must be fulfilled for accurate concentration measurements in trace-gas analysis of polar molecules.
© 2001 Optical Society of America
Andreas Schmohl, Andras Miklos, and Peter Hess, "Effects of Adsorption-Desorption Processes on the Response Time and Accuracy of Photoacoustic Detection of Ammonia," Appl. Opt. 40, 2571-2578 (2001)