TY - JOUR
T1 - Investigation of surface properties of ultrafine particles by application of a multistep condensation nucleus counter
AU - Niessner, R.
AU - Daeumer, B.
AU - Klockow, D.
N1 - Funding Information:
The authors gratefully acknowledge thc financial support of this work by the SFB 209 of the German Research Association and by the Fonds der Chemischen Industrie (VCI).
PY - 1990/1/1
Y1 - 1990/1/1
N2 - The fate of atmospheric ultrafine particles is determined by their size, chemical composition, and especially by their physical and chemical surface properties. To characterize the surface of ultrafine particles, their behavior as condensation nuclei can be used. Monodisperse ultra-fine particles with different surface structures were investigated by observing the onset of droplet formation at a fixed electrical mobility diameter. Droplet growth was detected by application of a multistep condensation nucleus counter (CNC). The particles were generated under well-controlled conditions and monodisperse fractions were obtained using an electrostatic classifier. For studying the influence of changes in the surface structure, ultrafine sulfuric acid droplets were coated with different organic materials. Different surface films required different supersaturations for droplet growth depending on the molecular structure and layer thickness of the material used for coating. Therefore it was concluded that certain compounds, enriched on the particle surface, affect condensation of water vapor in such a way that higher supersaturations are required in comparison to the particle core material. Additionally, it was observed that remarkably high supersaturations of water vapor were required for condensation on particles consisting of the following materials: Metals, carbon, and Aerosil (spherical silica particles).
AB - The fate of atmospheric ultrafine particles is determined by their size, chemical composition, and especially by their physical and chemical surface properties. To characterize the surface of ultrafine particles, their behavior as condensation nuclei can be used. Monodisperse ultra-fine particles with different surface structures were investigated by observing the onset of droplet formation at a fixed electrical mobility diameter. Droplet growth was detected by application of a multistep condensation nucleus counter (CNC). The particles were generated under well-controlled conditions and monodisperse fractions were obtained using an electrostatic classifier. For studying the influence of changes in the surface structure, ultrafine sulfuric acid droplets were coated with different organic materials. Different surface films required different supersaturations for droplet growth depending on the molecular structure and layer thickness of the material used for coating. Therefore it was concluded that certain compounds, enriched on the particle surface, affect condensation of water vapor in such a way that higher supersaturations are required in comparison to the particle core material. Additionally, it was observed that remarkably high supersaturations of water vapor were required for condensation on particles consisting of the following materials: Metals, carbon, and Aerosil (spherical silica particles).
UR - http://www.scopus.com/inward/record.url?scp=0025427135&partnerID=8YFLogxK
U2 - 10.1080/02786829008959406
DO - 10.1080/02786829008959406
M3 - Article
AN - SCOPUS:0025427135
SN - 0278-6826
VL - 12
SP - 953
EP - 963
JO - Aerosol Science and Technology
JF - Aerosol Science and Technology
IS - 4
ER -