Flow-cell designs thin-layer

There are two popular designs for the flow cells, a thin-layer design and a wall-jet design, both shown in Fig. 15. The potentiostats are generally of the... 

Fig. 10. Flow-through electrochemical cell designs. I, Planar geometries, thin-layer (A) and wall-jet (B) flow cell designs. II, Cylindrical geometries, open tubular (A), wire in a capillary (B), and packed-bed (C) flow cell designs...

Cells are classified according to how the working electrode is positioned relative to the flow stream. There are three major configurations tubular, thin layer, and wall jet. The tubular cell (open or packed) with its greater working electrode surface area is used for coulometric detection. The thin layer and wall jet designs are used for amperometric detector cells. In thin layer cells, the eluent flow is in the same plane as... 

Instrumentation. A cell design employing reticulated vitreous carbon as the working electrode material that enables both UV-Vis absorption and luminescence measurements has been described [47]. A thin-layer cell with a platinum working electrode has been developed [69]. The luminescence of the electrooxidation products of o-tolidine as a function of electrode potential was studied. A simplified flow cell design has been reported [70]. Luminescence spectra and fluorescence intensity for various aromatic compounds and their electrochemical and photochemical reaction products were observed as a function of flow rate, current and time after the potential step. In the latter study the electrooxidation of p-phenylenediamine (PPD) was examined. The cyclic voltammogram showed two oxidation peaks the first one is assumed to be caused by the formation of the radical cation according to... 

Figure 3.4 Simplified designs of chromatographic ED cells (a) Thin-layer cell (b) Wall jet cell (c) Tubular cell (d) Porous flow-through cell and (e) Single fibre electrode.

Zettersten C, Lomoth R, Hanunarstrom L, Sjoberg PJR, Nyhohn L (2006) The influence of the thin-layer flow cell design on the mass spectra when coupling electrochemistry to electrospray ionisation mass spectrometry. J Electroanal Chem 590(l) 90-99... 

FIG. 19. Automated flow electrodeposition system, initial design. Thin layer cell design. 

The two fundamental flow cell designs that were discussed differ essentially in the position of the working electrode relative to the direction of the eluent flow. The thin-layer cell exhibit laminar flow parallel to the electrode surface, while the wall-jet design exhibits a flow directiOTi perpendicular to the electrode surface. Comparative studies between the different cell designs were conducted. In spite of the fact that equations that describe the current as a function of the cell-type and geometries have been derived, comparison between the theoretical and experimental results was not satisfactory. The difference between the calculated and experimental was... 

Fig. 3. Diagrams of electrochemical cells used in flow systems for thin film deposition by EC-ALE. A) First small thin layer flow cell (modeled after electrochemical liquid chromatography detectors). A gasket defined the area where the deposition was performed, and solutions were pumped in and out though the top plate. Reproduced by permission from ref. [ 110]. B) H-cell design where the samples were suspended in the solutions, and solutions were filled and drained from below. Reproduced by permission from ref. [111]. C) Larger thin layer flow cell. This is very similar to that shown in 3A, except that the deposition area is larger and laminar flow is easier to develop because of the solution inlet and outlet designs. In addition, the opposite wall of the cell is a piece of ITO, used as the auxiliary electrode. It is transparent so the deposit can be monitored visually, and it provides an excellent current distribution. The reference electrode is incorporated right in the cell, as well. Adapted from ref. [113],...

As noted above, the deposits made with the H-cell design were thin, only about 0.4 ML/cycle. For a 200 cycle deposit, they appeared deep blue, the result of interference effects in the 30 nm thick film. With the new cycle program and large thin-layer flow-cell, the best deposits appeared gold in color, and ellipsometric measurement indicate they correspond to the deposition of very close to 1 ML/cycle. A study of the thickness as a function of the number of cycles is shown in Figure 18, where... 

Low efficiency cell designs (b) thin-layer (c) wall-jet. (d) High-efficiency cell design with porous working electrode in tube. Arrows indicate liquid flow... 

Figure 1 is representative of one choice that meets these criteria. Such a cell is normally described as a thin-layer sandwich configuration. The working electrode(s) is in the form of an interchangeable block. Electrodes of different sizes, shapes, or materials can be accommodated with a flow pattern established by a gasket shape and thickness. Such cells can easily be adapted for LC flow rates of from 5 to 5000 /rL/min. Different designs are used for capillary separation tools such as capillary electrophoresis (CE). 

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