Quadrupole-based glow discharge mass spectrometer: Design and results compared to secondary ion mass spectrometry analyses

Abstract

A design of quadrupole-based glow discharge mass spectrometer is briefly presented. A glow discharge occurs when a DC voltage (up to 3 kV) is applied between two electrodes in a cell filled with Ar at ∼1 hPa pressure. In this configuration, the sample acts as the cathode, and its surface (∼12 mm 2) is sputtered by impacting Ar ions. The sputtered neutral atoms are ionised downstream in the plasma, and are extracted through a diaphragm to an energy filter and quadrupole spectrometer (6 mm rods) in high vacuum. The processes of sputtering and ionisation are separated, therefore reducing matrix effects. Preliminary results of elemental analysis of stainless steel, chromium–vanadium steel, Al–Mg–Cu and Armco alloys are presented. These results are compared to secondary ion mass spectrometry (SIMS) results obtained for the same set of samples using a 5 keV Ar + ion beam and a quadrupole mass analyser (16 mm rods). The glow discharge mass spectrometry (GDMS) results allowed us to find SIMS relative sensitivity factors (RSF) for the analysed materials. Simple design and quick analysis time makes the new GDMS analyser an attractive tool in material technology.