Surface damage defects

Quantum well interface roughness Carrier or doping density Electron temperature Rotational relaxation times Viscosity Relative quantity Molecular weight Polymer conformation Radiative efficiency Surface damage Excited state lifetime Impurity or defect concentration... 

Ion implantation is often recommended as an efficient tool to enhance electrocatalysis either by disrupting the surface structure of the catalyst or by placing active atoms on an inactive (or less active) matrix. The latter possibility (which links this section with Section 3.3 devoted to adatoms) offers also a way to the use of extremely small amounts of active but expensive materials. In order to investigate the effect of surface damages, self-implantation or ion beam bombardment is the most appropriate approach. Implantation of Ni on Ni has led to a modest enhancement of the surface area, but not to electrocatalytic effects [279]. On the other hand, Pt bombarded with neutrons has shown an increase in the activity for hydrogen evolution [280]. However, it has been suggested that this is not related to the formation of surface defects, but rather to the effect of the radioactivity induced on the electrode and on the electrolyte. 

Once the disc insert is lapped or replaced, carefully dean the nozzle surface If defects are found, it is recommended that the nozzle be removed from the body. This can be cumbersome in some valve designs and is not recommended if not absolutely necessary. To remove the nozzle, turn the valve body over, taking care not to damage the bonnet studs. Turn the nozzle counterclockwise by using the wrench flats (if any) on the nozzle flange or a round nozzle wrench designed to clamp onto the nozzle flange... 

Finally, the migration of point defects from the damage layer can extend very much deeper into the solid, e.g., several microns below the surface. These defects can cause enhanced diffusion or segregation over this depth and result in changes in composition well beyond the ion range. Fig. 5 shows a schematic representation of the characteristic depths for the various mechanisms which are listed and characterized in Table 2. 

Surface treatment has been observed to change the breaking strength of carbon fibers. Bahl et al. [40] and Fitzer and Weiss [41] have observed that treatment of carbon fibers in nitric acid initially increases the fiber tensile strength. Continued anodization results in a loss in strength caused by fiber damage. This initial increase in strength can be explained by removal from the fiber surface of defects, which can initiate fracture. 

Rack Mark. A surface blemish on rolled glass resulting from a mechanical defect in the drive actuating the forming roller. Radial Crack. A semi-elliptical crack perpendicular to a surface damaged by pressing on to it a hard, sharp object. Radial Brick. A brick with the two end faces curved to form parts of concentric cylinders (cf. circle brick and see Fig. 1. p39)... 

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