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1.
Sensors (Basel) ; 15(9): 21315-26, 2015 Aug 28.
Article in English | MEDLINE | ID: mdl-26343670

ABSTRACT

Existing technologies for quantifying methane emissions are often limited to single point sensors, making large area environmental observations challenging. We demonstrate the operation of a remote, multi-path system using Chirped Laser Dispersion Spectroscopy (CLaDS) for quantification of atmospheric methane concentrations over extended areas, a technology that shows potential for monitoring emissions from wetlands.

2.
Appl Opt ; 51(7): B176-82, 2012 Mar 01.
Article in English | MEDLINE | ID: mdl-22410917

ABSTRACT

Identifying and implementing techniques for carbon management has become an important endeavor in the mitigation of global climate change. Two important techniques being pursued are geologic and terrestrial carbon sequestration. With regard to terrestrial sequestration, in order to accurately monitor changes in soil carbon potentially induced by sequestration practices, rapid, cost-effective, and accurate measurements must be developed. Spark-induced breakdown spectroscopy (SIBS) has the potential to be used as a field-deployable method to monitor changes in the concentration of carbon in soil. SIBS spectra in the 248 nm region of eight soils were collected, and the neutral carbon line at 247.85 nm was compared to total carbon concentration determined by standard dry combustion techniques. Additionally, Fe and Si emission lines were evaluated in a multivariate statistical model to evaluate their impacts on the model's predictive power for total carbon concentrations. The preliminary results indicate that SIBS is a viable method to quantify total carbon levels in soils, obtaining a correlation of (R(2)=0.972) between measured and predicated carbon in soils. These results show that multivariate analysis can be used to construct a calibration model for SIBS soil spectra.


Subject(s)
Carbon/analysis , Multivariate Analysis , Soil/analysis , Spectrum Analysis/methods , Iron/analysis , Silicon/analysis
3.
Appl Opt ; 44(31): 6635-43, 2005 Nov 01.
Article in English | MEDLINE | ID: mdl-16270552

ABSTRACT

We have demonstrated a high-sensitivity, room-temperature quantum-cascade (QC) laser sensor for detection of SO2 and SO3 under conditions relevant to aircraft test combustor exhaust. Two QC lasers probe infrared absorption features at 7.50 and 7.16 microm for SO2 and SO3, respectively, with a common dual-beam detection system. We inferred a noise-equivalent absorbance of approximately 1 x 10(-4) Hz(-1/2). We have demonstrated detection limits for both SO2 and SO3 of 1-2 ppmv m/Hz(1/2) (where ppmv is parts in 10(6) by volume) for 300 torr, elevated temperature, and path lengths near 1 m. This level of sensitivity permits measurement of < 1 ppmv of SO2 and SO3 at these conditions with modest signal averaging.

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