Production of vibrationally cold ions using a radio-frequency storage ion source

Abstract

A storage ion source has been built for the production of vibrationally cold H+2 and H+3 ions. Using a gas mixture of H2 and rare gases (Ne and He) in the source at high pressure, higher vibrational states of these ions have been effectively depleted by ion–molecule reactions and collisional deactivation. The internal energy of the cold ions was determined by the threshold measurement of collision-induced dissociation. With a mixture of H2 and Ne (ratio 1 : 5) in the source operated at 80 mTorr, H+2 ions were found to be in v=0 and 1 states only and the H+3 ions were in the ground vibrational state.