Experimental study of nucleation on ions with DBP vapor

Abstract

A new system for experimental investigation of ion-induced nucleation, based on a continuous flow-mixing type device, is introduced. Measurements of the ion-induced nucleation of dibutylphthalate (DBP) vapor in the presence of unipolar ions are presented. When an ionized water vapor/N2 mixture is contacted with DBP vapor, nucleation of DBP particles is significantly enhanced relative to that in the absence of ions for both positive and negative ions. The number concentration of DBP particles activated by ions increased with increasing ion number concentration and DBP supersaturation ratio. A definite ion polarity effect is observed; at equal saturation ratios, positive ions induce larger number concentration than negative ions. In the absence of water vapor, an ionized N2 stream produced nucleation rates higher than those for pure homogeneous nucleation but well below those in the presence of water vapor.