Forms and Oscillations Modes of Ion Cloud in the Linear RF-only Quadrupole Traps and in Ion Traps

摘要

Computer modelling of space configurations of ion clouds consisting of different m/z ions and dynamics of their motion in the presence of external (dipolar and quadrupolar) RF-field were analysed. Forms of ion clouds in ion traps were obtained by molecular modelling. It was shown that stratification of different m/z ions appears as a result of interaction of ion clouds with RF fields and with each other. For ions with high charge q = 30 e_(electron) and mass m = 30 000 m_(proton) (electrosprayed protein ions in ion guides and ion traps) at ion densities ～10~8 cm~(-3) stratification takes place even at room temperature. Coalescence of ion resonance frequencies for light and heavy equally charged ions in Paul ion trap was also demonstrated.