Design of a molecular beam surface ionization detector in combination with a quadrupole mass spectrometer

Abstract

Describes the design of an easily built and sensitive molecular beam detector suitable for molecules which can be handled by the surface ionization process. It has the advantages that is uses a round hot rhenium wire ensuring an ionization yield of 100% for most molecules, and that the whole system including ion deflection optics, quadrupole mass filter and ion multiplier can be positioned perpendicular to the molecular beam. The wire is placed in such a way that direct illumination of the multiplier is avoided. The theory of the ion deflection system is extensively treated and the results are compared with the experimental data. A maximum detection efficiency of 85% is obtained. The suitability of the combined round hot wire and ion deflection electrodes for an electron gun is under investigation).