Journal
ATMOSPHERIC CHEMISTRY AND PHYSICS
Volume 11, Issue 16, Pages 8735-8743Publisher
COPERNICUS GESELLSCHAFT MBH
DOI: 10.5194/acp-11-8735-2011
Keywords
-
Funding
- University of Delaware Center for Critical Zone Research
- American Chemical Society, Division of Analytical Chemistry
- Society for Analytical Chemists of Pittsburgh
- NSF [CHE-0808972]
Ask authors/readers for more resources
The distribution of charged species produced by electrospray of an ammonium sulfate solution in both positive and negative polarities is examined using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). Positively-charged ammonium bisulfate cluster composition differs significantly from negatively-charged cluster composition. For positively-charged clusters all sulfuric acid is neutralized to bisulfate, whereas for negatively-charged clusters the degree of sulfuric acid neutralization is cluster size-dependent. With increasing cluster size (and, therefore, a decreasing role of charge), both positively-and negatively-charged cluster compositions converge toward ammonium bisulfate. The reactivity of negatively-charged sulfuric acid-ammonia clusters with dimethylamine and ammonia is also investigated by FTICR-MS. Two series of negatively-charged clusters are investigated: [(HSO4)(H2SO4)(x)](-) and [(NH4)(x)(HSO4)(x+1)(H2SO4)(3)](-). Dimethylamine substitution for ammonia in [(NH4)(x)(HSO4)(x+1)(H2SO4)(3)](-) clusters is nearly collision-limited, and subsequent addition of dimethylamine to neutralize H2SO4 to bisulfate is within one order of magnitude of the substitution rate. Dimethylamine addition to [(HSO4)(H2SO4)(x)](-)clusters is either not observed or very slow. The results of this study indicate that amine chemistry will be evident and important only in large ambient negative ions (> m/z 400), whereas amine chemistry may be evident in small ambient positive ions. Addition of ammonia to unneutralized clusters occurs at a rate that is similar to 2-3 orders of magnitude slower than incorporation of dimethylamine either by substitution or addition. Therefore, in locations where amine levels are within a few orders of magnitude of ammonia levels, amine chemistry may compete favorably with ammonia chemistry.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available