Document Type


Publication Date

May 2007


The cloud condensation nuclei activity of organic coated ammonium sulfate particles was studied using a CCN counter in conjunction with the Aerodyne Aerosol Mass Spectrometer. The organic coatings studied were adipic acid, decanedioic acid (DEHS) and stearic acid. It was found, that the CCN activity of ammonium sulfate particles decreased as a function of insoluble (stearic, DEHS) and slightly soluble (adipic) organic coating on the surface of the aerosol particles. Due to the liquid state of DEHS, water molecules diffused through the coating and caused a slight increase in the critical supersaturation. Water was unable to diffuse through the thick and insoluble coating of stearic acid and caused the CCN activation of the ammonium sulfate core to be suppressed within the parameters of this experiment.



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