Helium glow discharges

TABLE 18. Limits of detection for various elements using the helium glow discharge detector (preliminary values) ... 

Table 147. Limits of Detection for Various Elements using the Helium Glow Discharge Detector (Preliminary Values)...

Figure 20.6 Example of an APR helium glow discharge. (Reproduced with permission from Prof. Denis Dowling).

Common gas chromatographic detectors that are not element- or metal-specific, atomic absorption and atomic emission detectors that are element-specific, and mass spectrometric detectors have all been used with the hydride systems. Flame atomic absorption and emission spectrometers do not have sufficiently low detection limits to be useful for trace element work. Atomic fluorescence [37] and molecular flame emission [38-40] were used by a few investigators only. The most frequently employed detectors are based on microwave-induced plasma emission, helium glow discharges, and quartz tube atomizers with atomic absorption spectrometers. A review of such systems as applied to the determination of arsenic, associated with an extensive bibliography, is available in the literature [36]. In addition, a continuous hydride generation system was coupled to a direct-current plasma emission spectrometer for the determination of arsenite, arsenate, and total arsenic in water and tuna fish samples [41]. 

Poljraer surfaces can be easily modified with microwave or radio-frequency-energized glow discharge techniques. The polymer surface cross-links or oxidizes, depending on the nature of the plasma atmosphere. Oxidizing (oxygen) and nonoxidizing (helium) plasmas can have a wide variety of effects on polymer surface wettability characteristics (92). 

Figure 21, Ultramicro instrument for Na and K estimation. Nanoliter specimen is placed on wire (inset) and is then vaporized in the glow discharge with helium (American Instrument Co,),...

Amano succeeded in observing the lowest rotational transition of the CH radical, generated by means of a glow discharge in mixture of CH4 and helium. The observation of this spectrum is a major achievement in microwave spectroscopy we show a part of the spectrum in figure 10.31, exhibiting two proton hyperfine lines, but defer a detailed discussion of the energy levels and spectrum until later in this chapter. 

The apparatus being used to treat polymer films is shown in Fig. 1(a) and for treatment of powders in Fig. 1(b). The surface analytical tools employed for characterizaton are X-ray photoelectron spectroscopy ( 50A), FTMIR ( lOOOOA) and contact angle measurements (first molecular layer), the details of vdiich have been previously described ( ). In the results being presented here, 5% and 15% premixtures of fluorine with helium are used in the fluorine glow discharge. 

DART uses a glow discharge plasma to excite a heated stream of inert gas, usually nitrogen or helium, which is directed onto the surface to be analyzed. These excited state atoms and molecules have been shown to effect,... 

In the case of a helium discharge sustained in a Grimm-type glow discharge lamp, vapors of halogenated hydrocarbons can be introduced successfully through... 

Christopher S. J., Hartenstein M. L., Marcus R. K., Belkin M. and Caruso J. A. (1998) Characterization of helium/argon working gas systems in a radiofrequency glow discharge atomic emission source. Part I ... 

Studies of a helium-operated gas-sampling Grimm-type glow discharge for the atomic emission spectrometric determination of chlorine in halogenated hydrocarbon vapors, Spectrochim Acta, Part B 53 1723-1735. 

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