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Proceedings Paper

Aerodyne research mobile infrared methane monitor
Author(s): J. Barry McManus; Paul L. Kebabian; Charles E. Kolb
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Paper Abstract

An improved real-time methane monitor based on infrared absorption of the 3.39 micron line of a HeNe laser is described. Real time in situ measurement of methane has important applications in stratospheric and tropospheric chemistry, especially when high accuracy measurements can be made rapidly, providing fine spatial-scale information. The methane instrument provides 5 ppb resolution in a 1 sec averaging time. A key feature in this instrument is the use of magnetic (Zeeman) broadening to achieve continuous tunability with constant output power over a range of 0.017/cm. The instruments optical absorption path length is 47 m through sampled air held at 50 torr in a multipass cell of the Herriott (off-axis resonator) type. A microprocessor controls laser frequency and amplitude and collects data with minimal operator attention. The instrument recently has been used to measure methane emissions from a variety of natural and artificial terrestrial sources.

Paper Details

Date Published: 1 May 1991
PDF: 10 pages
Proc. SPIE 1433, Measurement of Atmospheric Gases, (1 May 1991); doi: 10.1117/12.46173
Show Author Affiliations
J. Barry McManus, Aerodyne Research, Inc. (United States)
Paul L. Kebabian, Aerodyne Research, Inc. (United States)
Charles E. Kolb, Aerodyne Research, Inc. (United States)


Published in SPIE Proceedings Vol. 1433:
Measurement of Atmospheric Gases
Harold I. Schiff, Editor(s)

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