Study of the correlated motion of ion mixtures in an rf ion trap

We observed variations of the signal position versus the filament temperature, and thus the relative amounts of Ba⁺ and BaO⁺ ions stored simultaneously in an rf trap. The tendency of variations is explained by a generalized model of two coupled ion clouds, in which the coupling condition and the frequencies of correlated motions depend on the ion masses, the force constants of the applied trapping field and the Coulomb interaction between the ions as well as the relative ion numbers of the two ion clouds.