Cavity technique

In a nonattaching gas electron, thermalization occurs via vibrational, rotational, and elastic collisions. In attaching media, competitive scavenging occurs, sometimes accompanied by attachment-detachment equilibrium. In the gas phase, thermalization time is more significant than thermalization distance because of relatively large travel distances, thermalized electrons can be assumed to be homogeneously distributed. The experiments we review can be classified into four categories (1) microwave methods, (2) use of probes, (3) transient conductivity, and (4) recombination luminescence. Further microwave methods can be subdivided into four types (1) cross modulation, (2) resonance frequency shift, (3) absorption, and (4) cavity technique for collision frequency. 

The authors thank a number of collaborators for their excellent collaboration, particularly Dr. N. Kouchi. They also appreciate the early contribution to and the continuous development of the pulse radiolysis microwave conductivity/cavity technique by the late Dr. H. Shimamori. 

Dr Irwin Wieder, Dr R.R. Neiman Dr A.P. Rodgers of Interphase Corporation-West, Palo Alto, Calif studied the IR and UV radiation emitted by excited species in low-pressure gaseous C2H2/O2 explosions in order to establish the population distribution in selected energy levels. In the UV they used cavity techniques, and found a relative enhancement of several electronic transitions in CH and OH radicals. In the IR the emission from excited CO2 molecules which form behind a fast detonation... 

Collision-induced microwave spectra. Measurements of the dielectric loss by resonant cavity techniques at 9 and 24 GHz were first reported by Birnbaum and Maryott [33], The cavity was at room temperature and filled with carbon dioxide gas at densities up to 100 amagat. The loss, which at not too low frequencies increases as the square of density,... 

Figure 4. Measured energy loss of pastes of yeast cells and of monocellular algae at 53 GHz as a function of temperature. The energy loss of ice is shown for comparison. All curves have been normalized to unity at —196°C. The measurements were performed with the untuned-cavity technique.

A review is given on the physical and chemical reactions that occur if atomic hydrogen, hydrocarbon radicals, and low-energy ions interact with carbonaceous surfaces. In a first set of experiments the surface loss probabilities of different hydrocarbon radicals are determined in low-temperature plasmas using the cavity technique. The following values were determined / (C2H) = 0.90 0.05, / (C2H3) = 0.35 0.15, and / (CH3, C2H5) < KT2. 

An elegant yet technically simple method to determine surface loss probabilities is the cavity technique [30,36-38] A cavity with a small entrance slit (see Fig. 11.2) or a different well-defined geometry - [39-41] is exposed to a flux of reactive species. The transport of the particles is studied via the cross-sectional film thickness profiles. The dimensions of the geometry are chosen much smaller than the mean free path of the neutral radical species so that gas phase collisions are negligible. Then the normalized profiles depend on the surface loss probability (3 only. If the total fluence of particles into the slit is not known no conclusions can be drawn concerning the sticking coefficient except s < / . 

The surface loss probability of a species of interest can be determined using the cavity technique as described in Sect. 11.3.1. So far, cavity probes have been applied in low-temperature plasma experiments in the laboratory and in the fusion experiments JET and ASDEX Upgrade. 

Shimamori H, Tatsumi Y, Ogawa Y, Sunagawa T. (1992) Low-energy electron attachment to molecules studied by pulse-radiolysis microwave-cavity technique combined with microwave heating. J Chem Phys 97 6335-6347. 

EPR Parameters. The EPR spectra of the kerogens were recorded on a Varian V-4500 spectrometer using the dual cavity technique (5). By... 

To account for the polarization effects, the enzyme surrounding to a first approximation can he considered as a homogenous polarizable medium, which can he modeled using some dielectric cavity techniques. In addition, to model the steric effects that the enzyme surrounding imposes on the active site, it has been shown to be very useful to simply fix atoms at the edge of the active site model. The combination of continuum solvation and the coordinate-locking scheme represents a quite simple but yet powerful way to account for the parts of the enzyme that are not included in the model. 

Solvation corrections are calculated using the cavity techniques discussed above. The conductor-like polarizable continuum model (CPCM) is used." ... 

D. W. Alderman, D. M. Grant, A Cavity Technique for Use in High-Field Superconducting Probes, Abstracts of the 21st Experimental NMR Conference, Tallahassee, FL. 1980. 

Figure 5 Left panel Rate constants k for electron attachment to as a function of the mean collisional energy. (From Ref. 118.) (O) The results obtained using the pulse radiolysis microwave cavity technique combined with microwave electron heating ( ) previous results by Shimamori et al. [J. Chem. Phys. 1993, 99, 7789] ( ) electron swarm [Spyrous and Christophorou, J. Chem. Phys. 1985, 82, 1048] and (O) high-Rydberg atom beams [Marawar et al., J. Chem. Phys. 1988, 88, 2853]. Right panel Comparison of the cross section cr(s) for attachment to C5F5 as a function of the electron energy, (—) derived by unfolding the rate constants (From Ref. 118.) with the previous cross...

The general principles involved arc set out in I EC 377. Part 1 [10]. Resonant cavity techniques are specified in Part 2 of this standard. Further parts specifying other procedures may be developed. 

Guilminot E, Corcella A, Chatenet M, Maillard F (2007) Comparing the thin-film rotating disk eleetrode and the ultramicroelectrode with cavity techniques to study earbon-supported platinum for proton exchange membrane fuel cell applications. J Electroanal Chem 599 (1) 111-120... 

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