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Heterogeneous Interactions of ClONO2 and HCl with Sulfuric Acid Tetrahydrate: Implications for the StratosphereThe reaction probabilities for ClONO2+H2O- HOCl + HNO3 and ClONO2+ HCl Cl2 +HNO3 have been investigated on sulfuric acid tetrahydrate (SAT, H2SO4-4H2O)surfaces at temperatures between 190 and 230 K and at reactant concentrations that are typical in the lower stratosphere, using a fast-flow reactor coupled to a quadrupole mass spectrometer. The results indicate that the reaction probabilities as well as HCl uptake depend strongly on the thermodynamic state of SAT surface: they decrease significantly with decreasing H2O partial pressure at a given temperature, and decrease with increasing temperature at a given H2O partial pressure, as the SAT changes from the H2O-rich form to the H2SO4-rich form. For H2O-rich SAT at 195 K gamma(sub 1) approx. = -0.01 and gamma(sub 2) greater or equal to 0.1, whereas the values for H2SO4-rich SAT decrease by more than 2 orders of magnitude. At low concentrations of HCl, close to those found in the stratosphere, the amount of HCl taken up by H2O-rich SAT films corresponds to a coverage of the order of a tenth of a monolayer (approx. = 10(exp 14) molecules/sq cm); H2SO4-rich SAT films take up 2 orders of magnitude less HCl (les than 10(exp 12) molecules/sq cm). Substantial HCl uptake at high HCl concentrations is also observed, as a result of surface melting. The data reveal that frozen stratospheric sulfate aerosols may play an important role in chlorine activation in the winter polar stratosphere via processes similar to those occurring on the surfaces of polar stratospheric cloud particles.
Document ID
19980213324
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
External Source(s)
doi:10.1021/j100054a022
Authors
Zhang, Renyi (Massachusetts Inst. of Tech. Cambridge, MA United States)
Jayne, John T. (Massachusetts Inst. of Tech. Cambridge, MA United States)
Molina, Mario J. (Massachusetts Inst. of Tech. Cambridge, MA United States)
Date Acquired
September 6, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Journal of Physical Chemistry
Publisher: American Chemical Society
Volume: 98
Issue: 3
ISSN: 0022-3654
Subject Category
Geophysics
Report/Patent Number
NASA/CR-1994-205113
NAS 1.26:205113
Funding Number(s)
CONTRACT_GRANT: NSF ATM-90-17150
CONTRACT_GRANT: NAG2-632
Distribution Limits
Public
Copyright
Public Use Permitted.

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