Experimental Measurement of Competitive Ion-Induced and Binary Homogeneous Nucleation in SO₂/H₂O/N₂Mixtures

Abstract

Alpha-ray radiolysis of SO,/H,O/N, gas mixtures is carried out to investigate the competitive processes of ion-induced and binary homogeneous nucleation in this system.Charged particles in the system are indicative of ion-induced nucleation and most likely involve water clusters.Charged particle neutralization was prevented by application of a dc electric field, therefore, uncharged particles in the system result from homogeneous nucleation.Hydroxyl (.OH) radicals are generated by the a-ray radiolysis.Oxidation of SO, by .OH radicals leads to sulfuric acid (H,SO,) vapor molecules and to subsequent binary homogeneous nucleation of H,SO,/H,O.At increased SO2 concentrations the contribution of binary homogeneous nucleation increases relative to that of ion-induced nucleation.Electrical mobility distributions of bipolar ions and nanometer-sized charged particles were measured with a cluster-differential mobility analyzer combined with a Faraday cup electrometer.In this system, ion-induced nucleation occurred preferentially on negative rather than positive ions.