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We describe a portable diode-laser-based sensor for NH(3) detection using vibrational overtone absorption spectroscopy at 1.53 mum. Use of fiber-coupled optical elements makes such a trace gas sensor rugged and easy to align. On-line data acquisition and processing requiring <30 s can be performed with a laptop PC running LabVIEW software. The gas sensor(More)
A Kalman filtering technique is applied to the simultaneous detection of NH3 and CO2 with a diode-laser-based sensor operating at 1.53 micrometers. This technique is developed for improving the sensitivity and precision of trace gas concentration levels based on direct overtone laser absorption spectroscopy in the presence of various sensor noise sources.(More)
Regression models coupled with time series data were used to analyze the contribution of primary and secondary sources to formaldehyde (HCHO) concentrations, as determined by statistical analogy to primary (carbon monoxide, CO) and secondary (ozone, O 3) compounds measured simultaneously in Houston, TX. Time series analyses substantiated the need for(More)
A laser spectrometer based on difference-frequency generation in periodically poled LiNbO3 (PPLN) has been used to quantify atmospheric formaldehyde with a detection limit of 0.32 parts per billion in a given volume (ppbV) using specifically developed data-processing techniques. With state-of-the-art fiber-coupled diode-laser pump sources at 1083 nm and(More)
A one-week in situ intercomparison campaign was completed on the Rice University campus for measuring HCHO using three different techniques, including a novel optical sensor based on difference frequency generation (DFG) operating at room temperature. Two chemical derivatization methods, 2,4-dinitrophenylhydrazine (DNPH) and o-(2,3,4,5,6-pentafluorobenzyl)(More)
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