Clustering of Sulfur Dioxide and Water Vapor about Oxonium and Nitric Oxide Ions

The mobilities of ions produced in electrical discharges in the presence of trace quantities of water vapor and sulfur dioxide are generally lower than those expected for simple ions. Mass spectrometric identification reveals that species composed of water vapor and sulfur dioxide molecules clustering about common atmospheric ions are formed under these conditions. The identification of these clusters provides an explanation for the effect of trace gases on the mobilities of ions.