Glow discharge sputter-atomization

GDMS Glow Discharge Mass Spectroscopy Sample forms the cathode for a D.C. glow discharge Sputtered atoms ionized in plasma Ions - analyzed in mass spectrometer 0.1-100 pm 3-4 mm (Bulk) trace element analysis deleclion limit sub-ppb 9,10... 

In Volume 21, Part A, the preparation of a-Si H by rf and dc glow discharges, sputtering, ion-cluster beam, CVD, and homo-CVD techniques is discussed along with the characteristics of the silane plasma and the resultant atomic and electronic structure and characteristics. 

Use of glow-discharge and the related, but geometrically distinct, hoUow-cathode sources involves plasma-induced sputtering and excitation (93). Such sources are commonly employed as sources of resonance-line emission in atomic absorption spectroscopy. The analyte is vaporized in a flame at 2000—3400 K. Absorption of the plasma source light in the flame indicates the presence and amount of specific elements (86). 

Figure 1 Schematic of DC glow-discharge atomization and ionization processes. The sample is the cathode for a DC discharge in 1 Torr Ar. Ions accelerated across the cathode dark space onto the sample sputter surface atoms into the plasma (a). Atoms are ionized in collisions with metastable plasma atoms and with energetic plasma electrons. Atoms sputtered from the sample (cathode) diffuse through the plasma (b). Atoms ionized in the region of the cell exit aperture and passing through are taken into the mass spectrometer for analysis. The largest fraction condenses on the discharge cell (anode) wall.

A plasma is a hot, partially-ionized gas that effectively excites and ionizes atoms [366, 534, 535]. A glow discharge is low-pressure plasma maintained between two electrodes. It is particularly effective at sputtering and ionizing material from solid surfaces. 

GD, 112-113,113(f) dark space, 112 Grimm source, 112 sputtering, 112 Glow discharge. See GD Graphite furnace. See Electrothermal atomizers Gratings. 

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