A hybrid BEQQ mass spectrometer

Abstract

A new hybrid mass spectrometer of BEQQ geometry (B, magnetic sector; E, electric sector; Q, quadrupole mass filter) is described. The high resolution (BE) stage is interfaced to the double quadrupole (QQ) stage by a deceleration lens system (dual zoom lens with intermediate d.c. quadrupole) which also shapes the beam. The four reaction regions provide capabilities for both low- and high-energy MS/MS experiments, for exact mass measurements, and for sequential reactions in different regions. Provision is also made for energy and angle-resolved measurements which provide controlled energy deposition in selected ions. Needle collision cells are used in the first and third reaction regions. The r.f.-only quadrupole is encased in a gas-tight shroud and serves as a focussing device for collisions occurring in a laboratory energy range commonly 1–100 eV but sometimes considerably more. Capabilities are in place for recording parent, daughter and neutral species loss spectra associated with reactions in the collision quadrupole as well as the first and second field-free regions. High-resolution selection of the parent ions is possible. More complex scans are accessed through links between the electric and magnetic sector controls (provided by a linked scan microprocessor) and a system of microprocessors which controls the lens and quadrupole voltages.