Preparation and photoelectron spectrum of the CH3I- anion: Rare gas cluster mediated synthesis of an ion-radical complex

We report the preparation of the bare and argon-solvated anion of CH^sub 3^I, and characterize this species using negative ion photoelectron spectroscopy at 3.495 eV. The photoelectron spectrum consists of a narrow band appearing 0.11±0.02 eV above the binding energy of isolated iodide. Such behavior is similar to that displayed by iodide-(closed shell) solvent molecule complexes, indicating that photodetachment does not access the bound region of the CH^sub 3^I potential. These observations suggest that CH^sub 3^I^sup -^ rearranges (after electron capture) to an ion-radical complex. We advance the hypothesis that this complex adopts a C^sub 2v^ structure where the ion is hydrogen bonded to the methyl radical.