Discharging cells

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.

Using external chargers, the discharged cells are removed from the battery-operated device and placed in an approved RAM charger where the cell terminals make proper contact for charging. This is the appropriate method when RAM cells are used in applications designed also for... 

As current is drawn from the cell, the positive electrode voltage is depressed due to concentration polarization as sulphuric acid within the pores is consumed. This effect is more marked for partially discharged cells. Formation of lead sulphate decreases the pore volume and produces a microporous film on the Pb02 matrix. 

Perhaps one of the most severe limitations of glow discharge mass spectrometry is that any contaminants entering the discharge cell along with the support gas have a... 

Finally, we wish to mention that, at Harvard University, another laser spectroscopy experiment was carried out in a discharge cell, and not in a clean environment as the metastable helium beam of the other experiments. The uncertainty of this unpublished measurement is 8 kHz [11], probably due to systematic effects from collisions in the helium cell [13]. 

Fig. 8. Time evolution of the relative frequency of the (a)23S —> 23Pi(i/i) and (b)23S —> 23Po(i/o) transitions of helium at 1083 nm with respect to the master laser frequency (vm), alternatively locked on the 23S —> 2 helium transition in a RF discharge cell (o points), or on one hyperfine component of the B-X P(105) 29-0 I2 line ( points). Av = (i/ii0 — vm) — 2291.35987 MHz for o points, and Av = (iu,o — Vm) — 13319.69872 MHz for points. The error bars are one standard deviation of the fit (see text)...

Fig. 8.19. Glow-discharge cell used as a furnace atomization non-thermal excitation source with electrothermal atomization. (Reproduced with permission of the American Chemical Society.)...

Halides. The author is aware of only one example of the preparation of a ternary halide in an electric discharge. Massey and Urch (36) obtained a very small sample of impure SiCl3BCl2 as a by-product from the mercury discharge synthesis of B0CI4. The silicon probably originated from the quartz discharge cell used. It appears that the essentially unexplored study of mixtures of halides in electric discharges is worthy of study. 

Since this cell design has a slight excess of SO2, all of the lithium will be reacted when the battery is fully discharged. Therefore, contents of a discharged cell should be ... 

Plasma sources are capable of producing intense emission from the elements. Types of plasma used in chromatographic detection are microwave induced plasmas (MIP) and inductively coupled plasma (ICP). An argon plasma is sustained in a microwave cavity which focuses into a capillary discharge cell. The most widely used cavities are cyhndrical resonance cavities and surfatron that operates by surface microwave propagation along a plasma column. Atmospheric pressure cavities are very simple to interface with capillary GC columns. 

Principally two versions of spirally rolled RAM cells can be produced fully charged and nearly discharged cells. The Mn02 cathode can either be partly or completely prereduced in a batch process [48] and the zinc anode may consist mainly of zinc oxide. This special version is easier to manufacture and the shelf life in the nearly discharged state is probably unlimited. But initial charging is required for a 100 % discharge capacity of the first cycle. 

Fig. 12.27 Schematic diagram of a discharge cell for RF-glow discharge atomic emission spectroscopy.

The electromotive force of the self-discharged cell Pb H2 H2S04 PbS04 Pb can be determined from the equation ... 

Fig. 8. Doppler-shift discharge cell and optical arrangement.

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