 |
| Titel |
Laboratory study on new particle formation from the reaction OH + SO2: influence of experimental conditions, H2O vapour, NH3 and the amine tert-butylamine on the overall process |
| VerfasserIn |
T. Berndt, F. Stratmann, M. Sipilä, J. Vanhanen, T. Petäjä, J. Mikkilä, A. Grüner, G. Spindler, R. Lee Mauldin III, J. Curtius, M. Kulmala  , J. Heintzenberg |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 15 ; Nr. 10, no. 15 (2010-08-03), S.7101-7116 |
| Datensatznummer |
250008673
|
| Publikation (Nr.) |
 copernicus.org/acp-10-7101-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| Nucleation experiments starting from the reaction of OH radicals with SO2
have been performed in the IfT-LFT flow tube under atmospheric conditions at
293±0.5 K for a relative humidity of 13–61%. The presence of
different additives (H2, CO, 1,3,5-trimethylbenzene) for adjusting the
OH radical concentration and resulting OH levels in the range (4–300)
×105 molecule cm−3 did not influence the nucleation
process itself. The number of detected particles as well as the threshold
H2SO4 concentration needed for nucleation was found to be strongly
dependent on the counting efficiency of the used counting devices.
High-sensitivity particle counters allowed the measurement of freshly
nucleated particles with diameters down to about 1.5 nm. A parameterization
of the experimental data was developed using power law equations for
H2SO4 and H2O vapour. The exponent for H2SO4 from
different measurement series was in the range of 1.7–2.1 being in good
agreement with those arising from analysis of nucleation events in the
atmosphere. For increasing relative humidity, an increase of the particle
number was observed. The exponent for H2O vapour was found to be 3.1
representing an upper limit. Addition of 1.2×1011 molecule cm−3
or 1.2×1012 molecule cm−3 of NH3 (range of
atmospheric NH3 peak concentrations) revealed that NH3 has a
measureable, promoting effect on the nucleation rate under these conditions.
The promoting effect was found to be more pronounced for relatively dry
conditions, i.e. a rise of the particle number by 1–2 orders of magnitude
at RH = 13% and only by a factor of 2–5 at RH = 47% (NH3
addition: 1.2×1012 molecule cm−3). Using the amine
tert-butylamine instead of NH3, the enhancing impact of the base for
nucleation and particle growth appears to be stronger. Tert-butylamine
addition of about 1010 molecule cm−3 at RH = 13% enhances
particle formation by about two orders of magnitude, while for NH3 only
a small or negligible effect on nucleation in this range of concentration
appeared. This suggests that amines can strongly influence atmospheric
H2SO4-H2O nucleation and are probably promising candidates
for explaining existing discrepancies between theory and
observations. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|