Articles | Volume 10, issue 8
Atmos. Chem. Phys., 10, 3495–3503, 2010
https://doi.org/10.5194/acp-10-3495-2010
Atmos. Chem. Phys., 10, 3495–3503, 2010
https://doi.org/10.5194/acp-10-3495-2010

  16 Apr 2010

16 Apr 2010

Amine exchange into ammonium bisulfate and ammonium nitrate nuclei

B. R. Bzdek, D. P. Ridge, and M. V. Johnston B. R. Bzdek et al.
  • Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA

Abstract. The exchange kinetics and thermodynamics of amines for ammonia in small (1–2 nm diameter) ammonium bisulfate and ammonium nitrate clusters were investigated using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Ammonium salt clusters were reacted with amine gas at constant pressure to determine the kinetics of exchange. The reverse reactions, where aminium salt clusters reacted with ammonia gas, were also studied, and no substitution of ammonia for amine was observed. Gibbs free energy changes for these substitutions were determined to be highly exothermic, −7 kJ/mol or more negative in all cases. Uptake coefficients (reaction probabilities) were found to be near unity, implying that complete exchange of ammonia in small clusters by amine would be expected to occur within several seconds to minutes in the ambient atmosphere. These results suggest that if salt clusters are a component of the sub-3 nm cluster pool, they are likely to be aminium salts rather than ammonium salts, even if they were initially formed as ammonium salts.

Download
Altmetrics
Final-revised paper
Preprint