Abstract
Measurements of NH3 and CO2 were made in bioreactor vent gases with distributed-feedback diode-laser sensors operating near 2 µm. 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.
© 2001 Optical Society of America
Full Article | PDF ArticleMore Like This
Ricardo Claps, Florian V. Englich, Darrin P. Leleux, Dirk Richter, Frank K. Tittel, and Robert F. Curl
Appl. Opt. 40(24) 4387-4394 (2001)
Michael E. Webber, Suhong Kim, Scott T. Sanders, Douglas S. Baer, Ronald K. Hanson, and Yuji Ikeda
Appl. Opt. 40(6) 821-828 (2001)
Michael E. Webber, Douglas S. Baer, and Ronald K. Hanson
Appl. Opt. 40(12) 2031-2042 (2001)