Introduction and Principles

In addition to the amperometric feedback mode described above, other amperometric operation modes are also possible. For example, in the substrate generation/tip collection (SG/TC) mode, ip is used to monitor the flux of electroactive species from the substrate and vice versa for the tip generation/substrate collection (TG/SC) mode. These operation modes will be described in Section 12.3.1.3 and are useful in studies of homogeneous reactions that occur in the tip-substrate gap (see Section 12.4.2) and also in the evaluation of catalytic activities of different materials for useful reactions, e.g., oxygen reduction and hydrogen oxidation (see Section 12.4.3). In addition to the amperometric methods, other techniques, e.g., potentiometric method is also applicable for SECM and will be discussed in Section 12.3.2. We will also update the techniques suitable for the preparation of SECM amperometric tips in Section 12.3.1.1 and potentiometric probes in Section 12.3.2.2. 

The SECM can also be used as an imaging device (see Section 12.3.3), as an electrochemical tool for studies of surface reactivity of thin films (see Section 12.4.4) and as a high-resolution fabrication tool (see Section 12.4.5). Finally, the SECM can be adapted to probe the transport activity of biological systems Uke single cells, the ion transport across channels and enzyme activity (see Section 12.4.6). 

As SECM instrumentation has been extensively and thoroughly discussed in Chapter 2 of reference (1) and there are also commercial instruments (e.g., CH Instruments, Heka, and Uniscan) on the market, we mainly focus on experimental aspects encountered in imaging and tip positioning with SECM. Readers who are interested in the design of an SECM instrument can refer to that chapter. We also intend to include here an up-to-date account of the newly developed combined techniques so that interested individual investigators may appreciate the design of SECM-related techniques for their specific applications. 

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Contents Introduction and Principles. - The Reaction of Dichlorocarbene With Olefins. - Reactions of Dichlorocarbene With Non-Olefinic Substrates. -Dibromocarbene and Other Carbenes. - Synthesis of Ethers. - Synthesis of Esters. - Reactions of Cyanide Ion. - Reactions of Superoxide Ions. - Reactions of Other Nucleophiles. - Alkylation Reactions. - Oxidation Reactions. - Reduction Techniques. - Preparation and Reactions of Sulfur Containing Substrates. -Ylids. - Altered Reactivity. - Addendum Recent Developments in Phase Transfer Catalysis. 

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