Amines are likely to enhance neutral and ion-induced sulfuric acid-water nucleation in the atmosphere more effectively than ammonia

作者：Kurten T^*; Loukonen V; Vehkamaki H; Kulmala M

来源：Atmospheric Chemistry and Physics, 2008, 8(14): 4095-4103.

DOI：10.5194/acp-8-4095-2008

We have studied the structure and formation thermodynamics of dimer clusters containing H(2)SO(4) or HSO(4)(-) together with ammonia and seven different amines possibly present in the atmosphere, using the high-level ab initio methods RI-MP2 and RI-CC2. As expected from e. g. proton affinity data, the binding of all studied amine-H(2)SO(4) complexes is significantly stronger than that of NH(3)center dot H(2)SO(4), while most amine-HSO(4)(-) complexes are only somewhat more strongly bound than NH(3)center dot HSO(4)(-). Further calculations on larger cluster structures containing dimethylamine or ammonia together with two H(2)SO(4) molecules or one H(2)SO(4) molecule and one HSO(4)(-) ion demonstrate that amines, unlike ammonia, significantly assist the growth of not only neutral but also ionic clusters along the H(2)SO(4) co-ordinate. A sensitivity analysis indicates that the difference in complexation free energies for amine- and ammonia-containing clusters is large enough to overcome the mass-balance effect caused by the fact that the concentration of amines in the atmosphere is probably 2 or 3 orders of magnitude lower than that of ammonia. This implies that amines might be more important than ammonia in enhancing neutral and especially ioninduced sulfuric acid-water nucleation in the atmosphere.

• 出版日期2008