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.
- Surface reaction (mol. hydrate effects in heterogeneous interaction of gaseous ammonia with thin films of sulfuric acid monohydrate)
- Atmospheric aerosols (surface mol. hydrate effects in heterogeneous interaction of gaseous ammonia with thin films of sulfuric acid monohydrate)
- surface mol hydrate heterogeneous interaction ammonia sulfuric acid monohydrate