Mass selective ejection by axial resonant excitation from a linear ion trap.

We describe a new mass selective ejection method from a linear ion trap, which we call axial resonant excitation (AREX). A set of vane lenses are inserted between each quadrupole rod to produce electrostatic potential that is approximately harmonic along the central axis of the quadrupole field. After ions with specific m/z are resonantly oscillated in the axial direction, the ions are mass selectively ejected in the axial direction. At a high scan rate of 11 Th/ms, AREX achieved a high ejection efficiency of more than 60%, which is more than three times higher than a conventional mass selective axial ejection method from a linear trap using fringing field.