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 effects that water can have on both atomization and ionization in the plasma 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 nitrogen coil is used to aid in the removal and control of the water vapor content in the ion source. Different sample cathodes are investigated and shown to exhibit varying effects in the presence of water vapor. Sputtering reactive metals, such as getters, may minimize the extent of the water problems.