Published June 10, 2006
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Journal Article
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Stable isotopic analysis of atmospheric methane by infrared spectroscopy by use of diode laser difference-frequency generation
Abstract
An infrared absorption spectrometer has been constructed to measure the stable isotopic composition of atmospheric methane samples. The spectrometer employs periodically poled lithium niobate to generate 15 μW of tunable difference-frequency radiation from two near-infrared diode lasers that probe the ν3 rotational-vibrational band of methane at 3.4 μm. To enhance the signal, methane is extracted from 25 l of air by use of a cryogenic chromatographic column and is expanded into the multipass cell for analysis. A measurement precision of 12‰ is demonstrated for both δ13C and δD.
Additional Information
© 2006 Optical Society of America Received 14 October 2005; revised 25 January 2006; accepted 26 January 2006; posted 26 January 2006 The authors are grateful to the Environmental Protection Agency (STAR Fellowship); the National Research Council (Postdoctoral Research Associateship Program); and the Fundacão de Amparo a Pesquisa do Estado de São Paulo, Brazil, for financial support of this work. The authors thank E. Dlugokencky at the National Oceanic and Atmospheric Administration's Earth System Research Laboratory for providing calibrated ambient air samples.Files
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- Eprint ID
- 5390
- Resolver ID
- CaltechAUTHORS:TRUao06
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2006-10-16Created from EPrint's datestamp field
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2019-10-02Created from EPrint's last_modified field