Microcell designs

Fig. 16.2. Schematic microcell designs W = working electrode, A = auxiliary electrode, R = reference electrode some designs use a 2-electrode cell, (a) Droplet cells with solution on a surface containing (i) one or (ii) three microelectrodes, (b) Microchamber cells with electrodes (i) on the walls or (ii) in solution.

The exact cell design and the material used for its construction are selected according to the experiment at hand and the nature of the sample. The various designs differ with respect to size, temperature control capability, stirring requirement, shape, or number of cell compartments. Various microcells with 20-500 pL volumes can be used when the sample volume is limited. Particularly attractive are thin-layer cells in which the entire sample is confined within... 

Design of catalytic systems based on microcell models. 

If the catalytic system of Eu salts-CHjCOOH (or CF3COOH)-Zn powder is deprived of one of its components, the partial oxidation of alkanes and epoxidation of alkenes occur very slowly or not at all. These observations suggest that the concept of designing catalytic systems based on the microcell model in Figure 7 may be justified. 

Finally in this section, a Raman spectroelectrochemical microcell [17] is shown in Fig. 7. Having a total volume of 80 pi, this cell is particularly well suited to work with rare and/or expensive samples, such as biological compounds. Its design enables it to be used with a microscope objective as the laser focusing and Raman collection element. Such an arrangement... 

The cell design shown in Fig. 2c has been used for micro-SERS spectroscopy of chromosomes and related material This microcell is for use in a Raman microspectrometer using epi-illumination. By choice of the objective used in the microscope, the focus of the laser beam is about 6 pm in diameter for a typical chromosome micro-SERS-spectrum. The working electrode, with a diameter of 0.5 mm, is fitted into a perspex rod and can be screwed into a frame for positioning the electrode surface to the objective of the microscope. This small microcell needs only 0.08 ml of sample. 

Figure 3.14 shows a type of fixed-thickness microcell used for liquids. One can use as little as 0.02 ml of liquid in cells of regular design. Cells holding and little dead space have been made with 0.1-mm spacers. Demountable cells holding 0.1-0.5 t can be used with nonvolatile liquids. As little as 0.02 1 of material can be used for recording spectra if slits are masked and spacers reduced to 0.02 mm. The spectrum of the 727 cm band of toluene has been recorded by means of 90-100% ordinate scale expansion (Stewart, n.d.) on only 86 x 10 liter in a cell of 0.02 mm thickness and 1 mm area. 

YOO 08] Yoon J., Baca A.J., Park S.l. et al, Ultrathin sihcon solar microcells for semitransparent, mechanically flexible and microconcentrator module designs , Nature Materials, vol. 7, pp. 907-915, 2008. 

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