 |
| Titel |
Ammonia in positively charged pre-nucleation clusters: a quantum-chemical study and atmospheric implications |
| VerfasserIn |
A. B. Nadykto, F. Yu, J. Herb |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 12 ; Nr. 9, no. 12 (2009-06-18), S.4031-4038 |
| Datensatznummer |
250007434
|
| Publikation (Nr.) |
 copernicus.org/acp-9-4031-2009.pdf |
|
|
|
|
|
| Zusammenfassung |
| The quantum-chemical treatment of pre-nucleation clusters consisting of
atmospheric nucleation precursors is critically important for the
understanding of the molecular nature of atmospheric nucleation. In the
present study, the influence of ammonia on the thermochemical stability of
positively charged pre-nucleation clusters has been studied using the
Density Functional Theory (DFT). The formation of binary
(NH4+)(H2O)n and ternary
(NH4+)(H2SO4)(H2O)n ionic clusters and the
conversion of (H3O+)(H2O)n−1 into (NH4+)(H2O)n
and (H3O+) (H2SO4)(H2O)n−1 into
(NH4+)(H2SO4)(H2O)n have been investigated.
The thermochemical analysis carried out in the present study shows both
(H3O+)(H2O)n−1→(NH4+) (H2O)n and
(H2SO4)(H3O+)(H2O)n−1→(NH4+)(H2SO4) (H2O)n
transformations to be
favorable thermodynamically and gives us a clear indication of the important
role of ammonia in the conversion of positively charged clusters containing
hydronium (H3O+) into those containing protonated ammonia. Under
typical continental boundary layer condition, a large fraction of small
positive ions may contain ammonia, but most of neutral and negative hydrated
sulfuric acid monomers do not contain ammonia. In term of absolute
concentrations, around 1000 cm−3 out of 107 cm−3 of sulfuric
acid momoners contain ammonia. (NH4)+(H2O)n clusters
appear to dominate the concentrations of small positive ions. Because of the
weak affinity of sulfuric acid molecules to (H3O+)(H2O)n
and (NH4+)(H2O)n ions (n≤6), the concentrations
of both ammoniated and un-ammoniated sulfuric acid water proton clusters are
quite low. The atmospheric implications of the obtained results are
discussed. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|