Neutral-particle emission from multiply charged biomolecular ions in collisions with electrons

Electrostatic storage rings are suitable for storing macromolecules, such as biomolecules. The combination of electrostatic storage rings and electron targets opens up a new aspect for studying electron-biomolecular ion collisions with well-defined energies in the gas-phase. Neutral-particle emissions in collisions of electrons with biomolecular ions, studied by the electrostatic storage rings with the electron targets, are reviewed. In electron-biomolecular anion collisions, high threshold energies for producing neutrals are a common remarkable feature. Meanwhile, in electron-biomolecular cation collisions, resonant neutral particle emissions were observed in some specific ions and at particular energies. The origins of these phenomena are discussed based on well-known concepts in physics, chemistry and biology.