Improved interfacing of a field ionization source with a quadrupole mass analyzer

Abstract

Significant improvement of interfacing field ionization (FI) sources with quadrupole mass analyzers (QMA) has been achieved by placing a ferrite insert at the detector end of the QMA and by installing a repeller electrode opposite the electron multiplier (EM). By installing a multipoint FI source ca. 1 cm from the entrance to a QMA, operated at a resolution of 250, a molar counting efficiency of ca. 3 × 10 17 counts mol −1 has been achieved. This is comparable to that obtained with a sector magnet mass analyzer at the same resolution.