Use of Radio-Frequency Plasma

Use of Radio-Frequency Plasma in Chemical Synthesis S. M. L. Hamblyn and B. G. Reuben... 

A completely different approach might be the use of radio frequency plasma instead of a DC plasma. The ignition and sustainment of the plasma is decoupled from the application of voltages to the electrodes that are now used only for electrochemical reactions. Another method which has been proven to be quite successful is the application of an U-shaped tube in order to avoid an IR-drop over the ionic liquid (see Figure 10.2). Unfortunately, this set-up led to a large size distribution of the obtained particles but it showed that RF plasma could further improve the stability of the ionic liquids during the metal deposition process. 

Hamblyn, S.M.L. and Reuben, B.G. (1975) Use of radio-frequency plasma in chemical synthesis. Adv. Inorg. Radio Chem., 17, 89. 

This laboratory long ago devised [120] the use of radio-frequency dielectric spectroscopy [121, 122] for the on-line and real-time estimation of microbial and other cellular biomass during laboratory and industrial fermentations. The principle of operation is that only intact cells (see [123] for what is meant in this context by the word viable ), and nothing else likely to be in a fermentor, have intact plasma membranes and that the measurement of the electrical properties of these membranes allows the direct estimation of cellular biomass (Fig. 4). 

Nakagama T, Maeda T, Uchiyama K, Hobo T (2003) Monitoring nano-flow rate of water by atomic emission detection using helium radio-frequency plasma. Analyst 128(6) 543-546... 

The most common frequencies in use for CVD are micro-wave (MW) at 2.45 GHz and, to a lesser degree, radio frequency (RF) at 13. 45 MHz (the use of these frequencies must comply with federal regulations). A microwave-plasma deposition apparatus (for the deposition of polycrystalline diamond) is shown schematically in Fig. 5.18 (see Ch. 7, Sec. 3.4). 

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... 

The chemical and petrographic properties of the twenty coals used in the hydrogenation experiments are shown in Tables II and III. Mineral matter was determined directly using a radio frequency low temperature plasma asher at medium power rating for approximately 48 h per coal. The volatile matter was corrected for the effects of the mineral matter by applying the equation used by Given et al (5). 

Radiochemical purification, activation analysis and, 1 322-323 Radio-frequency plasmas commercial applications of, 17 110, 111 economics of, 17 111, 112 use of, in chemical synthesis, 17 89-112 Radioisotopes, use in medical diagnosis and imaging, 36 25-26... 

Reductive nitrosylation, transition metal nitrosyl complexes, 34 296-297 ReFejSj cluster, 38 41-43 self-assembly system, 38 41-42 Refining, of actinide metals, see Actinide, metals, purification Refractory compounds heat treatment of solids, 17 105-110 crystal growth, 17 105, 106 decomposition, 17 107,-110 spheroidization, 17 106, 107 preparation of, using radio-frequency plasma, 17 99-102... 

The use of antimicrobial additives has been mentioned in section 12.7.2, but another route has also been investigated, the deposition of silver nanoparticles, under formaldehyde-radio frequency plasma conditions, onto food-grade silicone rubber. The bacteriocidal properties of the silver-coated surfaces were investigated by exposing them to Listeria monocytogenes, with no bacteria being detected after exposure times of 12 to 18 hours. 

More recently, the parent system has been investigated under radio frequency plasma conditions. The plasma generated by an electric discharge provides an unusual medium for reactions in the gas phase. The free electrons that are present in the plasma are responsible for the chemical reactions that take place. The electrons are accelerated by an applied electric field and collide with the molecule, thereby activating it for the reaction. Most procedures employ radio frequency (RF) discharges so as to keep the pressure, temperature and energy of the system relatively low. The substrate is usually volatilized into the plasma zone with residence times of the order of a second. Because there is no need of chromo-phores, the technique has been used to activate those cases that are inert to the normal photoexcitation in solution, e.g. the parent 1,4-pentadiene. ... 

---