Local deposition, confined

To overcome this constraint, we performed experiments where we applied very short voltage pulses of only nanoseconds duration to an STM tip in electrochemical environment. The limited diffusion of the ions during such short voltage pulses prevented the ion distribution in the electrolyte from equilibration and indeed led to confinement of the electrochemical reactions on a nanometer scale. This method is demonstrated for the formation of holes of about 5-nm diameter and up to 3 monolayers (ML) depth on an Au(l 11) surface by local anodic dissolution of Au and for the local deposition of Cu clusters of similar dimensions by reduction of Cu ions from a CUSO4 electrolyte [16,17]. These experiments are reviewed and compared... 

The corrosion rates for both maraging steel and the low alloy steels in seawater are similar initially, but from about 1 year onwards the maraging steels tend to corrode more slowly as indicated in Fig. 3.32. The corrosion rates for both low alloy and maraging steel increase with water velocity . During sea-water exposure the initial attack was confined to local anodic areas, whereas other areas (cathodic) remained almost free from attack the latter were covered with a calcareous deposit typical of cathodic areas in sea-water exposure. In time, the anodic rust areas covered the entire surface. ... 

Photochemistry of course plays a crucial role in the whole of tropospheric atmospheric chemistry, not just in locally confined events such as those involving acid deposition discussed above, and in the weU-documented photochemical smog of Californian cities, which is now a local problem of very widespread incidence throughout the world. 

Since the first observation of the formation of defect-free three-dimensional (3D) islands in the early stage of germanium deposition on silicon, the growth of Ge/Si self-assembled quantum dots has attracted a considerable interest [1]. The carrier localization, the three-dimensional confinement, the high Ge content achieved with the heterostructures represent specific advantages for a new generation of devices... 

The application of ultra short voltage pulses between a tool electrode and a workpiece in an electrochemical environment allows the three-dimensional machining of conducting materials with sub-micrometer precision. The principle is based on the finite time constant for double-layer charging, which varies linearly with the local separation between the electrodes. During nanosecond pulses, the electrochemical reactions are confined to electrode regions in close proximity. The technique was used for local etching of copper and silicon as well as for local copper deposition. ... 

---