Radio-frequency glow discharges

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). 

Several types of continuous discharges are easily available in the laboratory. These are radio frequency, Townsend, coronas, glows (normal and abnormal), and arcs. Each system possesses special characteristics which in effect govern the motion of charged particles between the electrodes, and apart from a few special cases the systems are too complex to lend themselves to simple analytical description for studying ion-molecule reactions. Here, two of the latter systems—namely, coronas and glows—will be treated in detail in order to demonstrate their feasibility for studying both exothermic and endothermic reactions. 

Low-temperature glow-discharges were utilized to cause bond rupture in hexafluoroethane (11). In these experiments, the power to support the discharge was supplied by a radio-frequency discharge that delivered 25 W of power, at a frequency of 8.6 MHz, to the copper coil surrounding the Pyrex reactor (see Fig. 2). The load coil was indue-... 

A new synthesis for sigma-bonded, metal alkyls and similar compounds, involving a reaction between metal vapor and free radicals generated in a radio-frequency glow-discharge, has been reported (35). 

FIG. I. Schematic of a-C H plasma deposition by radio-frequency glow-discharge (RFPECVD). 

The radio-frequency glow-discharge method [30-34] has been the most used method in the study of a-C H films. In this chapter, it is referred to as RFPECVD (radio frequency plasma enhanced chemical vapor deposition). Film deposition by RFPECVD is usually performed in a parallel-plate reactor, as shown in Figure 1. The plasma discharge is established between an RF-powered electrode and the other one, which is maintained at ground potential. The hydrocarbon gas or vapor is fed at a controlled flow to the reactor, which is previously evacuated to background pressures below lO"" Torr. The RF power is fed to the substrate electrode... 

S. DeGendt, R.E. Van Grieken, S.K. Ohorodnik and W.W. Harrison, Parameter evaluation for the analysis of oxide-based samples with radio frequency glow discharge mass spectrometry, Anal. Chem., 67 (1995) 1026-1033. 

RFGD Radio-Frequency Glow-Discharge Plasma Deposition... 

D. Hill, T. Jawhari, J.G. Cespedes, J.A. Garcia and E. Bertran, In-situ monitoring of laser annealing by micro-Raman spectroscopy for hydrogenated silicon nanoparticles produced in radio frequency glow discharge, Phys. Status SolidiA, 203, 1296-1300 (2006). 

Direct Current and Radio Frequency Glow Discharge Operation... 

Analytical glow discharges have conventionally operated with a constant negative dc potential applied to the cathode. There is no reason, however, that they can t be operated through the application of a pulsed potential, an applied rf potential, or a positive potential applied to the cathode. Many variations have been tried alone and in combination with one another. Perhaps the most interesting among these (because of the unique capabilities that it provides) is the radio-frequency-powered discharge. The analysis of nonconductors is covered extensively in a later chapter, but a brief overview is in order here. 

This chapter deals exclusively with the methods that have been developed for the direct solids analysis of nonconductive samples by glow discharge mass spectrometry. The basic approaches to operation and sample preparation for the three primary methodologies of compaction, secondary cathode, and radio frequency powering are described. Examples of source performance and practical applications of each are taken from the analytical literature. Whereas this chapter de-... 

Analytical Radio Frequency Glow Discharge Mass Spectrometry... 

Figure 7 Radio frequency glow discharge mass spectrometry (rf GD-MS) source designs employed on a VG GloQuad instrument for the analysis of a, Pin-type samples. (From Ref. 28.) b, Flat samples. (From Ref. 29.)...

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