Studies of Ion Collisions in Ion Traps

Ion traps afford the opportunity to study the collisions of ions at or below electronvolt energies: energies typically much lower than are possible with conventional ion beams. Long observation times in traps permit investigations with small cross sections, and controlled multiple collisions of projectiles with the same stored particle lead to the possibility of the preparation of particular ionic states for study. Experimental efforts in ion storage have been directed toward the production of ions with higher charge, ion confinement with lower energy, and toward the optimization of certain measurements, in parallel with the study of collision interactions. A significant theoretical effort has been directed at low energy electron transfer collisions of multi-charged ions with hydrogen atoms, and with helium and molecular hydrogen as well. Certain measurements of electron transfer from H2 and H to stored, multi-charged ions are discussed.