RADIO-FREQUENCY MASS SELECTIVE EXCITATION AND RESONANT EJECTION OF IONS IN A THREE-DIMENSIONAL QUADRUPOLE ION TRAP.

Abstract

The three-dimensional quadrupole ion store (QUISTOR) has been used as a reactor for the study of ion/molecule reactions using external mass analysis, and as an ion trap for the investigation of stored ion dynamics using either external mass analysis or in situ resonant adsorption. Excitation of the axial frequency component of ion motion is accomplished by application of small rf potentials to an end-cap of the QUISTOR. The frequencies at which ion resonance is observed differ from those predicted by theory and are dependent upon the trapped ion density. Thus, the frequency shift may be related to both the space charge within the QUISTOR and perturbation of the stability diagram. The simultaneous application of in situ resonance absorption and external mass analysis has been utilized in three separate studies.