SPATIAL-DISTRIBUTION OF ATOMS IN A DC GLOW-DISCHARGE

An argon glow discharge acts as a reactive chemical cell involving sputtered analyte and argon atoms and ions. The spatial distribution of atoms from several samples has been monitored by an atomic absorption and emission arrangement simultaneously with mass spectrometric monitoring of the discharge. We have examined the effect of varying the sample to exit orifice distance on resultant atom profiles. Copper was studied by atomic absorption and iron by atomic emission, revealing complementary population shifts near the cathode surface. Argon metastable species were also monitored and correlated with the analyte response. Movement of the sample insertion probe by 90 degrees allowed a vertical perspective to be obtained for the discharge atom population. The effect of different discharge voltages was also examined to show sputter variations. Atom populations are defined by many factors, including sputter rate, diffusion rates, chemical reactivity, and discharge pressure.