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Issue 22, 2003
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The role of surface molecular hydrates in the heterogeneous interaction of NH3 with sulfuric acid monohydrate

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Abstract

The interaction of gaseous NH3 with thin films of sulfuric acid monohydrate (SAM, H3O+HSO4) in the 200–230 K range has been monitored by infrared spectroscopy and secondary ion mass spectrometry. The reaction occurs with the formation of the characteristic IR spectral features of the NH4+ and “salt” bisulfate ions, whilst loss of H3O+ and an additional surface species is observed. The evolution of the spectral features with time suggest that two processes are occurring at the uppermost surface layers, with a rapid initial reaction which saturates as the amount of available reactants on the surface is reduced and a slower continuous process which depends upon the transport of new reactants to and the removal of reaction products away from the surface. By comparison with the IR spectra of a variety of sulfuric acid hydrates, a surface reaction scheme is proposed and the implications of these observations for the reaction of condensed acids (sulfate aerosol) with bases in the atmosphere is discussed.

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Article information


Submitted
14 Jul 2003
Accepted
19 Sep 2003
First published
09 Oct 2003

Phys. Chem. Chem. Phys., 2003,5, 5101-5107
Article type
Paper

The role of surface molecular hydrates in the heterogeneous interaction of NH3 with sulfuric acid monohydrate

K. L. Nash, R. M. Sayer, S. B. Couling, J. Fletcher, A. Henderson, J. C. Vickerman and A. B. Horn, Phys. Chem. Chem. Phys., 2003, 5, 5101
DOI: 10.1039/B307967H

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