THE EFFECTS OF WATER-VAPOR IN GLOW-DISCHARGE MASS-SPECTROMETRY

Glow discharge mass spectrometry is used to determine various effects of water vapor on glow discharge plasma processes. The detrimental eff ects that water can have on both atomization and ionization in the pla sma are presented. Mass spectra taken with water concentrations up to 5% show that the primary species in the plasma arise from ion molecule reactions and water dissociation that occur in the plasma. A liquid n itrogen coil is used to aid in the removal and control of the water va por content in the ion source. Different sample cathodes are investiga ted and shown to exhibit varying effects in the presence of water vapo r. Sputtering reactive metals, such as getters, may minimize the exten t of the water problems.