Análisis externo: macro entorno

The chapters contained within this thesis are arranged as self-contained works; as such they introduce topics afresh. Following on from the introduction, chapter 2 introduces the principal components of the instrumentation built, which was used throughout the rest of the work. The following chapters each introduce experimental scenarios and theoretical techniques designed to interpret the data that arise. The first three of these represent major contributions to the

development or enhancement of important SEPMs. Chapter 3 concerns scanning ion conductance microscopy (SICM) and investigates the parameters which affect imaging resolution, an issue which has not been addressed appropriately before. Chapter 4 demonstrates the use of scanning electrochemical microscopy (SECM) for assessing the rate of growth of silver particles at a liquid/liquid interface. Chapter 5 looks at developing the tip position modulation (TPM) mode of SECM. A quantitative model is introduced, which incorporates convective mass-transport, and an experimental assessment of the technqiue is made. Chapters 6 and 7 introduce and develop two novel methodologies for assessing the electron transfer activity of heterogeneous electrodes, and focus particularly on highly oriented pyrolytic graphite (HOPG) as a substrate. Chapter 6 introduces a new scanned probe technique, the scanning microcapillary contact method (SMCM), which uses an electrolyte-containing capillary, only touching the substrate electrode with its meniscus, as the probe. In chapter 7 the methodology used involves applying a thin film on the electrode material that slows down diffusion. Variabilities that would be averaged out by diffusional overlap on typical voltammetric timescales in standard media are accessible. It is shown that recent high profile work which proposes that HOPG is inactive requires correction. Chapter 8 provides some conclusions of the work undertaken.

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Chapter 2: Building the