Enhancing effect of dimethylamine in sulfuric acid nucleation in the presence of water – a computational study
- 1Division of Atmospheric Sciences, Department of Physics, P. O. Box 64, 00014 University of Helsinki, Finland
- 2Laboratoire Thermodynamique et Interactions Moléculaires, Université Blaise Pascal, Clermont-Ferrand and CNRS,63177 Aubière, France
- 3Laboratoire de Météorologie Physique, OPGC/CNRS, Université Blaise Pascal, 24 avenue des Landais, 63170 Aubière, France
Abstract. We have studied the hydration of sulfuric acid – ammonia and sulfuric acid – dimethylamine clusters using quantum chemistry. We calculated the formation energies and thermodynamics for clusters of one ammonia or one dimethylamine molecule together with 1–2 sulfuric acid and 0–5 water molecules. The results indicate that dimethylamine enhances the addition of sulfuric acid to the clusters much more efficiently than ammonia when the number of water molecules in the cluster is either zero, or greater than two. Further hydrate distribution calculations reveal that practically all dimethylamine-containing two-acid clusters will remain unhydrated in tropospherically relevant circumstances, thus strongly suggesting that dimethylamine assists atmospheric sulfuric acid nucleation much more effectively than ammonia.