title: Detection of ammonia by photoacoustic spectroscopy with semiconductor lasers.
abstract: Sensitive photoacoustic detection of ammonia with near-infrared diode lasers (1.53 microns) and a novel differential acoustic resonator is described; a sensitivity of 0.2 parts per million volume (signal-to-noise ratio = 1) is attained. To eliminate adsorption-desorption processes of the polar NH3 molecules, a relatively high gas flow of 300 SCCM was used for the ammonia-nitrogen mixture. The results are compared with recent ammonia measurements with a NIR diode and absorption spectroscopy used for detection and photoacoustic experiments performed with an infrared quantum-cascade laser. The performance of the much simpler and more compact setup introduced here was comparable with these previous state-of-the-art measurements.
authors.affiliation: Institute of Physical Chemistry, University of Heidelberg, Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schmohl
authors.forename: András
authors.initials: A
authors.lastname: Miklós
authors.forename: Peter
authors.initials: P
authors.lastname: Hess