Aircraft instrument design for in-situ tropospheric OH measurements by laser-induced fluorescence at low pressures

William H. Brune, Philip S. Stevens, James H. Mather

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

The hydroxyl radical (OH) is important for many processes involved in tropospheric chemistry. For instance, it initiates the photochemical degradation of gases that cause global climate change, such as methane and the chlorofluorocarbon substitutes (HCFCs). Because of its reactivity, its abundances are less than 0.1 pptv. Thus, OH has been very difficult to measure accurately, despite its importance. Techniques have evolved, however, so that good measurements of tropospheric OH abundances are now possible. One of these techniques that is adaptable to aircraft measurements is the laser induced fluorescence detection of the OH radical in a detection chamber at low pressures, a technique first developed by R. J. O'Brien and T. M. Hard. Because OH is both excited and detected in the A2Σ+(υ′ = 0) → X2II(υ″ = 0) transition near 308 nm (approximately 10 milliwatts at 10 kHz repetition rate), significant laser generation of OH and interference signals from other trace gases are avoided. The current ground-based instrument, which can be readily adapted to aircraft, can detect OH abundances of 1.4 × 105 OH molecules cm-3 with S/N = 2 in 30 seconds, and 5 × 104 cm-3 in five minutes.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherPubl by Int Soc for Optical Engineering
Pages413-424
Number of pages12
ISBN (Print)0819408808
StatePublished - Jan 1 1993
EventOptical Methods in Atmospheric Chemistry - Berlin, Ger
Duration: Jun 22 1992Jun 24 1992

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume1715
ISSN (Print)0277-786X

Other

OtherOptical Methods in Atmospheric Chemistry
CityBerlin, Ger
Period6/22/926/24/92

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering

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    Brune, W. H., Stevens, P. S., & Mather, J. H. (1993). Aircraft instrument design for in-situ tropospheric OH measurements by laser-induced fluorescence at low pressures. In Proceedings of SPIE - The International Society for Optical Engineering (pp. 413-424). (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 1715). Publ by Int Soc for Optical Engineering.