Hollow cathode glow discharge

Whatever the analytical method and the determinand may be, the greatest care should be devoted to the proper selection and use of internal standards, careful preparation of blanks and adequate calibration to avoid serious mistakes. Today the Antarctic investigator has access to a multitude of analytical techniques, the scope, detection power and robustness of which were simply unthinkable only two decades ago. For chemical elements they encompass Atomic Absorption Spectrometry (AAS) [with Flame (F) and Electrothermal Atomization (ETA) and Hydride or Cold Vapor (HG or CV) generation]. Atomic Emission Spectrometry (AES) [with Inductively Coupled Plasma (ICP), Spark (S), Flame (F) and Glow Discharge/Hollow Cathode (HC/GD) emission sources], Atomic Fluorescence Spectrometry (AFS) [with HC/GD, Electrodeless Discharge (ED) and Laser Excitation (LE) sources and with the possibility of resorting to the important Isotope... 

Glow discharge lamp (analogous to hollow cathode lamp) in which the sample acts as the cathode. Attached to a standard atomic emission spectrometer. 

Figure 15.3 —Ionisation devices, a) Continuous current arc (globular technique). The electrodes are inserted in a series circuit having a variable resistor, a cell and a continuous power source of a few tens of volts b) Glow discharge device using argon (hollow cathode lamp type). Samples can be introduced as powders or non-conductive pellets.

Use of glow-discharge and the related, but geometrically distinct, hollow-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). 

The ionization of the gas can be achieved by electron beam vaporization [208], hollow cathode discharge [209, 210], glow discharge [34, 192], arc discharge [36], or glow discharge in a parallel magnetic field [33]. 

Hollow cathode discharges are perhaps the most common glow discharges used in analytical chemistry. Most spectroscopists are familiar with these devices as hollow cathode lamps used for atomic absorption spectroscopy. Figure 2.10 contains... 

Courier transformation infrared spectrometry. Hollow cathode glow discharge. rfHigh performance liquid chromatography. Ion chromatography. 

This technique is used mainly for surface analysis of electrically conductive materials provided that correction factors are applied if all components are known. The theory is based on the light emitted from a glowing discharge between a hollow cathode lamp and the sample (cathode) in an atmosphere of argon. Argon cations are formed which are accelerated in the direction of the negatively charged sample from which atoms are released, exited and quantified. 

The features of glow discharges can be realized in the hollow cathode and related sources, in glow discharges with flat cathodes with dc or rf power and in special sources such as the so-called gas-sampling glow discharges. 

Schepers C. and Broekaert J. A. C. (2000) The use of a hollow cathode glow discharge (HCGD) as an atomic emission spectrometric element specific detector for chlorine and bromine in gas chromatography, J Anal At Spectrom 15 51-65. 

Dempster M. A. and Marcus R. K. (2000) Optimization of hollow cathode diameter for particle beam/hollow cathode glow discharge atomic emission spectrometry, Spectrochim Acta, Part B 55 599-610. 

Deng R. C. and Williams P. (1994) Suppression of cluster ion interferences in glow discharge mass spectrometry by sampling high-energy ions from a reversed hollow cathode ion source, Anal Chem 66 1890-1896. 

Fig. 1. Schematic diagram of the hollow-cathode glow-discharge CVD and high-sensitivity white-light absorption spectroscopy apparatus. (Reprinted with permission from Menningen et ai, 1995a, Contrih. Plasma Phys. 35, 359, 1995 Wiley-VCH, Inc.)...

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