Glass diaphragm

When more experience is gained on microwave electrochemical phenomena, they could, for example, be used to characterize electrochemical systems in a contact-free way. The PMC signal alone could describe the system sufficiently for understanding its behavior. An interesting application would then be fast electrochemical sensors that, while implanted or separated by a glass diaphragm, could be scanned and evaluated without electrical contacts. 

When a species reduced at a cathode is oxidized at an anode, and vice versa, a two-compartment cell, namely a divided cell like an H-type cell (Figure 8.3) with a sintered glass diaphragm or an ion-exchange membrane should be used in order to prevent mixing of both anodic and cathodic solutions. To decrease the ceU voltage (voltage between an anode and cathode), the distance between both the electrodes should be kept as small as possible. 

The monocell consists of two compartments separated by a slntered-glass diaphragm, with Ti wire screen as the cathode and Pt coil as the anode. All experiments with this monocell were carried out with stirring at constant cathode potential. 

The ambient-pressure diaphragm-cell method was adapted and developed for high-pressure measurements by Woolf and co-workers in the 1970s. It retains the simplicity of the ambient-pressure glass diaphragm cell and has been used to obtain self-diffusion and intradiffusion coefficients over a wide temperature and pressure range to an accuracy of 1-2 per cent, which is in excellent agreement with self-diffusion measurements made with NMR techniques. 

Figure 2.6. Diaphragm diffusion cell after Dullien and Shemilt, 1961). A, light liquid compartment, B, heavy liquid compartment, C, stop-eoek D, E, capillaries, F, sintered glass diaphragm, G = polythene-coated iron stirrers, H, rotating magnets...

Variable focusing lenses with glass diaphragms. (Source Ahn, S.H. and Y.K. Kim. 1999. Sensors and Actuators A, 78(1), 48-53. With permission.)... 

When using instruments of this type, great care is needed in the initial standardization against buffers. Also, calomel electrodes having a sintered glass diaphragm can permit enough diffusion of potassium chloride to produce a drift of 0 03 pH unit in 24 hours. This defect can be remedied by... 

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