Performance improvements for RF-only quadrupole mass filters and linear quadrupole ion traps with axial ejection

摘要

A RF only quadrupole rod set mass filter or mass analyzer and a linear quadrupole ion trap with axial ejection are disclosed comprising a first pair of rod electrodes, a second pair of rod electrodes and an energy filter. The first pair of rod electrodes is longer than the second pair of rod electrodes. Ions having desired mass to charge ratios experience fringing fields at an exit region which results in the ions possessing sufficient axial kinetic energy to be transmitted by the energy filter. Other ions possess insufficient axial kinetic energy to be transmitted by the energy filter and are attenuated.

主权项

1. A quadrupole rod set mass filter, mass analyser or ion trap comprising;
a first pair of rod electrodes; a second pair of rod electrodes; and an energy filter; wherein said first pair of rod electrodes has a physical property which differs from a physical property of said second pair of rod electrodes; wherein said quadrupole rod set mass filter, mass analyser or ion trap further comprises a device arranged and adapted to apply a DC bias voltage to said first pair of electrodes or said second pair of electrodes in order to align ions with either said first pair of rod electrodes or said second pair of rod electrodes.