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Type: Journal article
Title: Measurements of NH₃ and CO₂ with distributed-feedback diode lasers near 2.0 μm in bioreactor vent gases
Other Titles: Measurements of NH(3) and CO(2) with distributed-feedback diode lasers near 2.0 micrometers in bioreactor vent gases
Author: Webber, M. E.
Claps, R.
Englich, Florian Viktor
Tittel, Frank K.
Jeffries, J. B.
Hanson, R. K.
Citation: Applied Optics, 2001; 40(24):4395-4403
Publisher: Optical Society of America
Issue Date: 2001
ISSN: 1539-4522
School/Discipline: School of Chemistry and Physics
Statement of
Michael E. Webber, Ricardo Claps, Florian V. Englich, Frank K. Tittel, Jay B. Jeffries, and Ronald K. Hanson
Abstract: Measurements of NH₃ and CO₂ were made in bioreactor vent gases with distributed-feedback diode-laser sensors operating near 2 mm. Calculated spectra of NH₃ and CO₂ were used to determine the optimum transitions for interrogating with an absorption sensor. For ammonia, a strong and isolated absorption transition at 5016.977 cm⁻¹ was selected for trace gas monitoring. For CO₂, an isolated transition at 5007.787 cm⁻¹ was selected to measure widely varying concentrations [500 parts per million (ppm) to 10%], with sufficient signal for low mole fractions and without being optically thick for high mole fractions. Using direct absorption and a 36-m total path-length multipass flow-through cell, we achieved a minimum detectivity of 0.25 ppm for NH₃ and 40 ppm for CO₂. We report on the quasi-continuous field measurements of NH₃ and CO₂ concentration in bioreactor vent gases that were recorded at NASA Johnson Space Center with a portable and automated sensor system over a 45-h data collection window.
Keywords: Absorption; Spectroscopy, diode lasers; Spectroscopy, infrared; Spectroscopy, molecular
Rights: © 2001 Optical Society of America
DOI: 10.1364/AO.40.004395
Appears in Collections:Physics publications

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