Open AccessMeasurement of prenucleation molecular clusters in the NH 3 , H 2 SO 4 , H 2 O system
Author(s) -
Hanson D. R.,
Eisele F. L.
Publication year - 2002
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001jd001100
Subject(s) - cluster (spacecraft) , ammonia , sulfuric acid , protonation , analytical chemistry (journal) , ion , molecule , ionization , materials science , chemistry , inorganic chemistry , environmental chemistry , organic chemistry , computer science , programming language
The molecular cluster ions HSO 4 − (H 2 SO 4 ) n− 1 (NH 3 ) m corresponding to the neutral species (H 2 SO 4 ) n (NH 3 ) m for n = 2 to 6 and m = 0 to n− 1 have been observed at temperatures up to ∼285 K. A transverse chemical ionization apparatus was located inside a cooled flow tube where water, sulfuric acid, and ammonia vapors mixed and formed clusters. The complexities of the experimental technique and the interpretation of the results are extensively discussed. Typical NH 3 and H 2 SO 4 concentrations were 2 × 10 9 cm −3 , i.e, ∼100 pptv at atmospheric pressure. For these conditions, cluster concentrations were estimated to be a few times 10 6 cm −3 and the critical, particle‐forming cluster likely contained 2 H 2 SO 4 molecules at 275 K. The results are consistent with the species (H 2 SO 4 ) 2 NH 3 playing an important role in the formation of new particles in the atmosphere.