Amine exchange into ammonium bisulfate and ammonium nitrate nuclei

B. R. Bzdek, D. P. Ridge, M. V. Johnston

Research output: Contribution to journalArticle (Academic Journal)peer-review

113 Citations (Scopus)

Abstract

The exchange kinetics and thermodynamics of amines for ammonia in small (1ĝ€"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.

Original languageEnglish
Pages (from-to)3495-3503
Number of pages9
JournalAtmospheric Chemistry and Physics
Volume10
Issue number8
Publication statusPublished - 2010

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