Surface density, etching

If we keep these reflections in mind, interpretation of the morphology of the GaP surface etched in alkaline K3Fe(CN)g solutions is straightforward. At the (lll)-fac the overall etch rate is kinetically controlled. The i-Fcurves for the p-type (111) GaP-face are schematically shown in Fig. 13 a, which demonstrates that the situation at the rest potential corresponds to the rising part of the anodic partial current density. Etch pits are formed due to local differences in hole capture reactivity, analogously to the anodic etching of p-GaP in the rising part of the i- V curve (Fig. 1... 

Swift heavy ion beams with extremely high LETs are used to degrade strongly polymer chains within tracks over a range of a few tens of micrometers. After irradiation, the top surface of bulk thermoplastics such as polyethyleneterephtalate, polycarbonate, polyvinylidene fluoride or polyimide materials as well as thin films made of the same material are subsequently etched by a wet chemical treatment that reveals pores of which the shape, surface density and dimensions can be controlled by choosing appropriate conditions. High aspect ratio cylindrical or conical traces of diameter ranging from a few nanometers to some... 

More recently, the same group applied the SECM in the feedback mode for the debromination of a surface-bound polymerization initiator. -phis caused that ATRP took place only on the areas, which were not debrominated. They reported that the surface reduction rate, controlled by the UME scan rate and the reducer strength, affected the dimensions of the patterns. The reducer strength allowed tuning the surface density of the initiator layer and then the elongation of the polymer brushes grown in the locally etched regions. 

Optical surface studies are useful in judging crystal perfection. Etched surfaces can provide quantitative information on internal surfaces and on line defects. Emerging dislocations show etch pits at the surfaces, and etch pit counting is a standard method for determining dislocation densities in metals. In copper, the method is extremely... 

Some nonhygroscopic materials such as metals, glass, and plastics, have the abiUty to capture water molecules within microscopic surface crevices, thus forming an invisible, noncontinuous surface film. The density of the film increases as the relative humidity increases. Thus, relative humidity must be held below the critical point at which metals may etch or at which the electrical resistance of insulating materials is significantly decreased. 

Process variables also play a significant part in determination of surface finish. For example, the higher the current density, generally the smoother the finish on the workpiece surface. Tests using nickel machined in HCl solution show that the surface finish improves from an etched to a poHshed appearance when the current density is increased from ca 8 to 19 A/cm and the flow velocity is held constant. A similar effect is achieved when the electrolyte velocity is increased. Bright smooth finishes are obtained over the main machining zone using both NaCl and NaNO electrolyte solutions and current densities of 45-75 A/cm. ... 

---