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Title: Photoacoustic measurement of ammonia in the atmosphere: influence of water vapor and carbon dioxide

Journal Article · · Applied Optics; (USA)
DOI:https://doi.org/10.1364/AO.29.003643· OSTI ID:6175247
; ;  [1]
  1. N. V. Tot Keuring van Elektrotechnische Materialen, Postbus 9035, NL-6800 ET Arnhem (The Netherlands)

The photoacoustic determination of the ammonia concentration in atmospheric air by absorption of CO{sub 2} laser radiation at 9.22 {mu}m is influenced by the presence of H{sub 2}O and CO{sub 2}. Kinetic cooling due to the coupling of excited CO{sub 2} and N{sub 2} levels causes important changes in phase and amplitude of the photoacoustic signal. Theoretical background is presented to deduce the correct NH{sub 3} concentration from the signal. The experimental setup used to perform field measurements is described. Adhesion of NH{sub 3} to the walls of the resonant photoacoustic cell was investigated. Temperature effects are treated. Field data of NH{sub 3} and H{sub 2}O concentrations are presented. Key words: Photoacoustics, ammonia, kinetic cooling, trace gas measurements, ammonia adhesion, acoustic resonance, CO{sub 2} laser radiation, water vapor absorption, carbon dioxide absorption.

OSTI ID:
6175247
Journal Information:
Applied Optics; (USA), Vol. 29:25; ISSN 0003-6935
Country of Publication:
United States
Language:
English