Microwave-plasma system

The substrate temperature should be kept between 800 and 1000°C and cooling may be necessary. Gas composition and other deposition parameters are similar to those used in a microwave-plasma system. Deposition rate is low, reported as 0.5 to 1 im/h. 

Baumann H, Heumann KG. 1987. Analysis of organobromine compounds and HBr in motorcar exhaust gases with a GC/microwave plasma system. Fresenius Zanal Chem 327 186-192. 

Kitagawa K, Nishimoto N. 1989. Thermal vaporizer - capacitively coupled microwave plasma system for trace mercury determination. J Spectrosc Soc Japan 38(4) 282-287. 

Microwave Plasma System for Surface Modification of Gas-Separating Polymer Membranes... 

Reamer et al used a Matronic gas chromatograph for the separation and introduction of alkyllead compounds into the detector. The detector consisted of a microwave plasma system which was basically the same as that described by McCormack et al 5 with some instrumental modifications. The system used was comprised of a transparent quartz capillary which contained the effluent from the GC (see Figure 170). 

Figure 5.2. Two of the more common types of low pressure CVD reactor, (a) Hot Filament Reactor - these utilise a continually pumped vacuum chamber, while process gases are metered in at carefully controlled rates (typically a total flow rate of a few hundred cubic centimetres per minute). Throttle valves maintain the pressure in the chamber at typically 20-30 torr, while a heater is used to bring the substrate up to a temperature of 700-900°C. The substrate to be coated - e.g. a piece of silicon or molybdenum - sits on the heater, a few millimetres beneath a tungsten filament, which is electrically heated to temperatures in excess of 2200 °C. (b) Microwave Plasma Reactor - in these systems, microwave power is coupled into the process gases via an antenna pointing into the chamber. The size of the chamber is altered by a sliding barrier to achieve maximum microwave power transfer, which results in a ball of hot, ionised gas (a plasma ball) sitting on top of the heated substrate, onto which the diamond film is deposited.

Atsuya and Akatsuka [140] have described a method for determining trace amounts of arsenic. The technique, which uses capacitively coupled microwave plasma with an arsine generation system, has been used to determine arsenic in sewage sludge. 

Diemer, J. and Heumann, K.G. (1997) Bromide/bromate speciation by NTI-IDMS and ICP-MS coupled with ion exchange chromatography. Fresenius J. Anal. Chem., 357,74-79. Duan, YX., Wu, M., Jin, Q.H. and Hieftje, G.M. (1995) Vapour generation of nonmetals coupled to microwave plasma-torch mass-spectrometry. Spectrochim. Acta B, 50,355-368. Ebdon, L., Hill, S. and Jones, R (1987) Interface system for directly coupled high performance liquid chromatography-flame atomic absorption spectrometry for trace metal determination./. Anal. At. Spectrom., 2, 205-210. 

Estes el al. [722] described a method for the measurement of triethyl- and trimethyllead chloride in potable water, using fused silica capillary column gas chromatography with microwave excited helium plasma lead specific detection. Element specific detection verified the elution of lead species, a definite advantage to the packed column method. The method involved the initial extraction of trialkyllead ions from water into benzene, which was then vacuum reduced to further concentrate the compounds. Direct injection of the vacuum concentrated solutions into the gas chromatography-microwave excited helium plasma system gave delectability of triethyllead chloride at the 30mg L 1 level... 

Pack et al. described the coupling of GC separations to TOF-MS by utilization of a microwave plasma torch (MPT) [50]. This low-power microwave plasma source has exhibited excellent limits of detection for halogenated species. When such species are separated by GC, the simultaneous capabilities of TOF-MS allowed the monitoring of 12C and 35C1 simultaneously, thereby facilitating the determination of empirical formulas. Presumably, ion chromatographic separations, FIA systems, and other separations might also benefit from the capabilities of TOF-MS. 

The fluorination of the inner surface of intravenous tubing, using atmospheric pressure plasma glow (APG), has been evaluated to enhance biocompatibility and suppress plasticiser migration (273). The effect of plasma treatment on the migration of DOA, and an EVA-carbon monoxide terpolymer as partial or complete replacement, into isooctane solution has given positive results (231). A closed system microwave plasma reactor was used to react imidazole molecules to PVC surfaces with the claim that the resulting PVC was useful as an implant for biomedical applications, on the basis of spectroscopic studies (368). 

Krushevska, A., Barnes, R.M., Amarasiriwaradena, C.J. Decomposition of biological samples for inductively coupled plasma atomic emission spectrometry using an open focused microwave digestion system. Analyst 118, 1175-1181 (1993)... 

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