Probing the Potential Barriers and Intramolecular Electrostatic Interactions in Free Doubly Charged Anions

Multiply charged anions, though ubiquitous in nature, have been difficult to produce and study in the gas phase. Photoelectron spectroscopy has been combined with an electrospray ion source to probe the repulsive Coulomb barriers, excess electron binding, and intramolecular electron-electron interactions in a series of dicarboxylate dianions, ^-O₂C(CH₂)ₙCO₂^- (n0ex0ex=0ex0ex3--10). These experiments provide quantitative information about the repulsive Coulomb barriers and how the excess electron binding energy and the barrier height depend on the intramolecular Coulomb repulsion.