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Experiments on the Temperature Dependence of Heterogeneous Nucleation on Nanometer‐Sized NaCl and Ag Particles
Author(s) -
Schobesberger Siegfried,
Winkler Paul M.,
Pinterich Tamara,
Vrtala Aron,
Kulmala Markku,
Wagner Paul E.
Publication year - 2010
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201000417
Subject(s) - nucleation , saturation (graph theory) , aerosol , contact angle , classical nucleation theory , condensation , chemistry , thermodynamics , nanometre , water vapor , propanol , materials science , analytical chemistry (journal) , composite material , chromatography , physics , mathematics , organic chemistry , combinatorics , methanol
Experimental investigations on the activation of NaCl and Ag aerosol particles by heterogeneous nucleation of n ‐propanol vapor at well‐defined vapor saturation ratios are presented. Particular emphasis is placed on the temperature dependence of this process from −11 to +14 °C. Aerosols are generated in a tube furnace and electrostatically classified at mean geometric mobility equivalent diameters between 3.6 and 11 nm. Activation probabilities are measured by means of expansion chamber experiments, and onset n ‐propanol saturation ratios are subsequently determined. The experiments with Ag particles do not produce any unexpected results. The results for NaCl particles, however, show a temperature trend of the onset saturation ratios that is opposite to that predicted by classical nucleation theory. This stresses the important role that surface properties play in heterogeneous nucleation processes. By tentatively assuming a temperature‐dependent contact angle, we are able to theoretically reproduce this reversed temperature trend. In addition, the shrinkage of NaCl condensation particles is investigated for varying amounts of n ‐propanol vapor, and contact angle measurements are performed at temperatures ranging from −7 to +30 °C.