Multiple ring electrodes

Figure 3.13 Using multiple ring electrodes to modify the electric field, (a) Experimental design, (b) Calculated lines of forces using a series of copper ring electrodes. Reproduced with permission from Deitzel et al. (2001 c). Copyright 2001. Elsevier.

Figure 4.9 Different types of collectors used in electrospinning (a) flat plate collector (KIdoaki et al. 2005) (6) rotating drum (Wannatong et al. 2004), mandrel (Mo and Weber 2004), rotating disc (Zussman et al. 2003) (c) rectangular, triangular, or wire cylinder frame (Katta et al. 2004) (d) electrode pair arrangements (Li, D., et al. 2003b) (e) single or multiple ring electrodes (Dalton et al. 2005) (f) mesh electrode (U.S. patent 6,110,590, Aug. 2000) (g) pair of cone-shaped collectors (Bunyan et al. 2006).

A special O-ring cell design is needed for in situ infrared (IR) vibrational characterization of an electrochemical interface. The absorption of one monolayer (i.e. <1015 cm 2 vibrators) can be measured if the silicon electrode is shaped as an attenuated total reflection (ATR) prism, which allows for working in a multiple-in-ternal-reflection geometry. A set-up as shown in Fig. 1.9 enhances the vibrational signal proportional to the number of reflections and restricts the equivalent path in the electrolyte to a value close to the product of the number of reflections by the penetration depth of the IR radiation in the electrolyte, which is typically a tenth of the wavelength. The best compromise in terms of sensitivity often leads to about ten reflections [Oz2]. 

Fig. 4 Schematic of an ion trap MS instrument. This device consists of two endcap electrodes (entrance and exit) and a ring electrode. An ion trap MS separates ions based on mass-to-charge ratio (m/z). Once ions are introduced into the ion trap MS, the radiofrequency (rf) amplitude is increased so that ions are sequentially ejected (by increasing mass) and detected. This type of MS provides a routine (i.e., benchtop) and sensitive detector using either GC and LC interfaces. Furthermore, this instrument provides a unique format for multiple stages of MS analysis (MS ). (Courtesy of ThermoFinnigan, San Jose, CA.)...

Metalloporphyrins consist of porphyrin ring structures complexed to a central atom. Among them, hemin structures with central iron atoms at different oxidation states and chlorophyll pigments containing magnesium are most abundant The interest in their spectroelectrochemical studies is multiple. Thus, their adsorption and electrochemical behaviour at the electrode surface can be used not only to model their functions in a biological matrix but also to improve the practical application of porphyrin coated electrodes as catalysts or sensitizers in photoelectrochemical cells... 

This method is very useful when multiple samples are arranged in a library array, with the test cell moving from one sample to another to perform PEC electrode characterizations, or when epoxy encasement is undesirable. To confine the electrolyte over the semiconductor area of interest, an O-ring is used to seal the contact between the electrode and test cell that contains the electrolyte. The O-ring should... 

The light absorption of reaction intermediates generated at the electrode surface can be monitored in transmission or in reflection mode, and this allows sensitive detection and/or quantitative kinetic studies. The sensitivity of this technique can be substantially improved by introducing cavity-ring-down cells [14] or multiple-reflection path cells. 

Taken together, the results of these large-scale simulations do not suggest that there should be any significant losses of performance with the addition of multiple holes up to 4 mm in diameter. Furthermore, and somewhat to our surprise, symmetric placement of holes in the ring electrode appears to be neither necessary nor particularly advantageous based on the results of these simulations. 

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