Probing electrostatic effects: Formation and characterization of zwitterionic ions and their 'neutral' counterparts in the gas phase

A dipolar ion and its nonzwitterionic counterpart were generated and characterized in the gas phase. A single charge site is found to be sufficient to lower the energy of a zwitterion well below its neutral counterpart. Charge separation in a dipolar anion enables hydrogen - deuterium exchange to take place with acids over an extraordinarily large range. These results provide a basis for studying electrostatic effects and understanding mass spectroscopic processes involving large biological molecules.