Role of Helium Droplets in Mass Spectra of Diatomics: Suppression of Dissociative Reactions

It is generally accepted that electron impact of doped helium nanodroplets initially produces a positively charged helium atom, which then ionizes the dopant if the two come into contact. In effect the He⁺ can initiate ion-molecule reactions. However, the effect of the surrounding helium on ion-molecule reactions remains ambiguous. To explore this, electron-induced chemistry has been investigated for the diatomic molecules O₂, CO and N₂. The helium is found to significantly suppress dissociative ion product channels.