학술논문
A fast-response chemical ionization mass spectrometer for in situ measurements of HNO[sub 3] in the upper troposphere and lower stratosphere.
Document Type
Article
Author
Neuman, J. A.; Neuman, J.A.; Gao, R. S.; Gao, R.S.; Schein, M. E.; Schein, M.E.; Ciciora, S. J.; Ciciora, S.J.; Holecek, J. C.; Holecek, J.C.; Thompson, T. L.; Thompson, T.L.; Winkler, R. H.; Winkler, R.H.; McLaughlin, R. J.; McLaughlin, R.J.; Northway, M. J.; Northway, M.J.; Richard, E. C.; Richard, E.C.
Source
Subject
*CHEMICAL ionization mass spectrometry
*NITRIC acid
*
Language
ISSN
0034-6748
Abstract
A chemical ionization mass spectrometer instrument has been developed for in situ measurements of nitric acid (HNO[sub 3]) in the upper troposphere and lower stratosphere from the NASA WB-57 aircraft. Fast and sensitive measurements of HNO[sub 3] are achieved by using a low surface area heated Teflon sampling inlet and detection techniques that employ ion-molecule reactions. Sensitivity to HNO[sub 3] is determined in flight by adding HNO[sub 3] from a calibrated HNO[sub 3] permeation source into the sample air flow, and instrument background is measured by displacing ambient air from the sampling inlet with a flow of dry nitrogen in the sampling inlet. Instrument temperatures, pressures, and gas flows are controlled in flight to maintain a constant detection sensitivity in a changing ambient operating environment. The initial performance of this new instrument is evaluated using HNO[sub 3] and ozone data obtained between 6 and 19 km during the 1999 NASA Atmospheric Chemistry of Combustion Emissions Near the Tropopause mission. The data reveal a sensitivity of 0.73 Hz/pptv, a detection limit of 30 pptv for 10 s integration times, and a fast time response (<1 s). Further reductions in the background HNO[sub 3] signal will improve performance. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]