Oxygen discharges

The lower the slope, the lower the activation loss for the O2 reduction reaction in acid media, the observed slope is 0.060 V/ decade and it can be obtained theoretically by assuming the oxygen discharge step as the slowest one (the rate determining step, the r.d.s. ( 7)). For hydrogen the mechanism is different and the r.d.s. is the atomic dissociation and in this case a Tafel slope of 0.030... 

Fig. 30. Electron micrographs of freshly cleaved chemically crosslinked polyurethane rubber, before (.4) and after (B) oxygen discharge etching (Spit 161a). Replication with polystyrene in chloroform (gelatin in water yields similar results). Rodlike structural elements of a few tenths of a micron are detectable in B. Reported...

Preliminary studies indicated that extensive water was formed as a reaction product when the metal-organic compounds were decomposed via an oxygen discharge. This water could be chemically incorporated into the oxide films when the substrates were held below a certain temperature which depended on the organic evaporation rate and the hygroscopic nature of the substrate. For instance, with NaCl substrates, the silica films were found to be free of water above 180°C. with a tetra-ethoxysilane evaporation rate of 0.015 cc./hour (5). The presence of silicic acid was detected below 180°C. by infrared transmission studies. 

The noncrystalline titanium oxide films were prepared from titanium tetraisopropylate while maintaining an oxygen discharge. Since titanium oxide is not a common glass-forming system, one may inquire whether the viscosity of such a film would be similar to that of glass near its transition region—i.e., 101 ,-1014 poises. For many undercooled systems,... 

Fig. 48. Atomic oxygen concentration, measured by optical emission actinometry, as a function of radius in a 13.56 MHz oxygen discharge sustained in a diode reactor. The electrode is covered with a reactive film up to a radius of 3.75 cm. This film acts as a sink for atomic oxygen (loading) resulting in significant radial concentration gradients. Such gradients are responsible for etch non-uniformity. Solid lines show the result of mathematical model predictions. After [231]. Pressure 2 torr, gas flow 100 seem.

Unlike ethanol oxidation, chronopotentiometric experiments of methanol and glycerol oxidation on Pd-(Ni-Zn)/C and Pd-(Ni-Zn-P)/C electrodes show a remarkable increase of the overpotential with time, the oxygen discharge potential being attained after 2.5 and 1.5 h with methanol and glycerol, respectively. In addition to decreasing the electrochemical stability of the electrodes, the oxidation of methanol and glycerol on Pd-(Ni-Zn)/C and Pd-(Ni-Zn-P)/C is also much slower tlm that of ethanol under comparable experimental conditions as shown by the CVs illustrated in Fig. 23. 

Schwarz-Selinger T, von Toussaint U, Hopf Ch, Jacob W (2009b) Fuel removal from tile gaps with oxygen discharges reactivity of neutrals. Phys Scr T138(014009) 8... 

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