Production of I₂⁺ from methyl iodide: Ion-molecule reactions under multiple collision conditions vs cluster chemistry

In this paper, we present the results of our investigations of the ionic reactions of methyl iodide, under multiple collision conditions as well as within the cluster environment. Utilizing a triple quadrupole mass spectrometer, the reactivity of various fragment ions {CD₃⁺, I⁺, I²⁺, and CD_xI⁺ (x = 0-3)} as they passed through a collision cell containing CH₃I were studied for a range of low-energy collisions. It was observed that under conditions of low collision energy, only the I⁺ ions react with methyl iodide to generate I₂⁺ ions. The reactions within methyl iodide clusters following electron-induced ionization were also studied. The various cluster ion sequences observed in the cluster mass spectrum of methyl iodide following electron-induced ionization can be rationalized on the basis of the ionic reactions of methyl iodide observed in the tandem mass spectrometric study.