Non-intrusive, in situ detection of ammonia in hot gas flows with mid-infrared degenerate four-wave mixing at 2.3μm

Summary, in English

We demonstrate non-intrusive, in situ detection of ammonia (NH₃) in reactive hot gas flows at atmospheric pressure using mid-infrared degenerate four-wave mixing (IR-DFWM). IR-DFWM excitation scans were performed in the v₂+v₃ and v₁+v₂ vibrational bands of NH₃ around 2.3μm for gas flow temperatures of 296, 550 and 820K. Simulations based on spectroscopic parameters from the HITRAN database have been compared with the measurements in order to identify the spectral lines, and an absorption spectrum at 296K has also been measured to compare with the IR-DFWM spectra. The signal-to-noise ratio of the IR-DFWM measurement was found to be higher than that of the absorption measurement. Some spectral lines in the measured IR-DFWM and absorption spectra had no matching lines in the HITRAN simulation. The detection limit of NH₃ diluted in N₂ with IR-DFWM in this spectral range was estimated at 296, 550 and 820K to be 1.36, 4.87 and 7.06×10¹⁶molecules/cm³. The dependence of the NH₃ IR-DFWM signal on the quenching properties of the buffer gas flow was investigated by comparing the signals for gas flows of N₂, Ar and CO₂ with small admixtures of NH₃. It was found that the signal dependence on buffer gas was large at room temperature but decreased at elevated temperatures. These results show the potential of IR-DFWM for detection of NH₃ in combustion environments.

• Author: A. L. Sahlberg; D. Hot; M. Aldén; Z. S. Li
• Department/s: Combustion Physics
• Publishing year: 2016-09
• Language: English
• Pages: 1140-1148
• Publication/Series: Journal of Raman Spectroscopy
• Volume: 47
• Issue: 9
• Links: http://dx.doi.org/10.1002/jrs.4882
• Document type: Journal article
• Publisher: John Wiley & Sons Inc.
• Topic: Atom and Molecular Physics and Optics
• Keywords: Ammonia; Degenerate four-wave mixing; Mid-infrared
• Status: Published
• ISBN/ISSN/Other: ISSN: 0377-0486