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Ion-assisted tropospheric OH measurement techniqueThe present technique measures atmospheric OH concentrations by first titrating OH into isotopically labeled H2(exp 34)SO4 by a series of gas phase reactions in an effectively wall-less flow tube reactor on a time-scale which is short in comparison to the OH lifetime. The gas phase H2SO4 concentration is then determined by reacting it with NO3(-)(center dot)HNO3 ions in a flow tube, and subsequently measuring the resulting (HSO4(-))/(NO3(-)) ion ratio. Since the determination of H2SO4 concentration does not depend on the measurement of an absolute photon flux or chemical concentration but rather only on the relative concentration measurement of two fairly similar mass ions in conjunction with a fixed reaction time and reaction rate coefficient, no in-field calibration technique should be required. The ion-assisted OH measurement technique provides a concentration measurement about once each 10 to 20 seconds and had a detection sensitivity less than or equal to 1 x 10(exp 5) molecules/cu cm (2 standard deviations) with an integration time of 5 minutes during the past field study. Typically, the total background signal level is in the low 10(exp 6) molecule/cu cm range with the scatter in this background (or background noise in 5 minutes) in the mid 10(exp 4) molecules/cu cm range.
Document ID
19940024098
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Eisele, Fred L.
(Georgia Inst. of Tech. Atlanta, GA, United States)
Date Acquired
September 6, 2013
Publication Date
February 1, 1994
Publication Information
Publication: SRI International Corp., Local Measurement of Tropospheric HO(x)
Subject Category
Environment Pollution
Accession Number
94N28601
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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