Scanning electrochemical cell design

While the first STM studies of electrode surfaces were performed with self-built instruments, scanning tunneling microscopes for electrochemical use are nowadays commercially available at a price that hardly justifies the effort of homemade equipment. Nevertheless, new instrumental designs are now and then discussed in the literature, which are still worthwhile to be considered for special applications. There is, however, additional equipment required for the operation of an electrochemical STM, for which homemade designs may be advantageous over commercially available ones and hence is briefly mentioned here in terms of tip preparation and isolation, the electrochemical cell, and vibration damping. 

One organic redox system that we have studied by transmission spectroelectrochemical measurements is chlorpromazine (CPZ) [118]. The electrochemistry and spectroscopy of CPZ have been investigated extensively over the years [22,30,179]. Figure 24A shows a cyclic voltammetric (background corrected) i-E curve for 100 gM CPZ + 10 mM HCIO4. The measurement was made in a specially designed, thin-layer electrochemical cell with a path length of 150 gm and a cell volume of 5 gL [118]. The scan... 

Special miniaturized cell designs are required for in situ studies with STM, scanning force microscopy (SFM), or scanning electrochemical microscopy (SEM) using ultra micro electrodes (UME) as imaging probes, which have to approach very close to the surface. Cell designs and the necessary equipment are described in the appropriate sections of other chapters. 

Mu and Kadish have described an ECESR cell with a thin layer design suitable for measurements at both ambient and low temperatures [617]. The thin layer of electrolyte solution is enclosed by the quartz tube inserted into the microwave cavity of the ESR spectrometer and a solid quartz rod fixed in the center of the tube. An expanded platinum mesh in the gap is used as the working electrode. At low electrode potential scan rates, the cell shows an acceptable electrochemical response. 

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