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| Titel |
Open-path, quantum cascade-laser-based sensor for high-resolution atmospheric ammonia measurements |
| VerfasserIn |
D. J. Miller, K. Sun, L. Tao, M. A. Khan, M. A. Zondlo |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 1 ; Nr. 7, no. 1 (2014-01-13), S.81-93 |
| Datensatznummer |
250115558
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| Publikation (Nr.) |
 copernicus.org/amt-7-81-2014.pdf |
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| Zusammenfassung |
| We demonstrate a compact, open-path, quantum cascade-laser-based atmospheric
ammonia sensor operating at 9.06 μm for high-sensitivity, high
temporal resolution, ground-based measurements. Atmospheric ammonia
(NH3) is a gas-phase precursor to fine particulate matter, with
implications for air quality and climate change. Currently, NH3 sensing
challenges have led to a lack of widespread in situ measurements. Our
open-path sensor configuration minimizes sampling artifacts associated with
NH3 surface adsorption onto inlet tubing and reduced pressure sampling
cells, as well as condensed-phase partitioning ambiguities. Multi-harmonic
wavelength modulation spectroscopy allows for selective and sensitive
detection of atmospheric pressure-broadened absorption features. An in-line
ethylene reference cell provides real-time calibration (±20%
accuracy) and normalization for instrument drift under rapidly changing field
conditions. The sensor has a sensitivity and noise-equivalent limit
(1σ) of 0.15 ppbv NH3 at 10 Hz, a mass of ~ 5 kg and
consumes ~ 50 W of electrical power. The total uncertainty in NH3
measurements is 0.20 ppbv NH3 ± 10%, based on a
spectroscopic calibration method. Field performance of this open-path
NH3 sensor is demonstrated, with 10 Hz time resolution and a large
dynamic response for in situ NH3 measurements. This sensor provides the
capabilities for improved in situ gas-phase NH3 sensing relevant for
emission source characterization and flux measurements. |
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