Reactive lift

As can be seen, the valve opening characteristics involve two steps, resulting in an expansive lift and a reactive lift (Figure 5.6). 

For chemically reactive metals such as Fe, Ni, Mo and W, etc., tip polishing is in general very simple. As shown in Fig. 3.5, a beaker is filled with three quarters of the recommended polishing solution. A piece of thin wire is mounted on a mechanical manipulator so that the wire can be dipped into the solution to a desirable depth, and can also be lifted out of the solution. Usually a section of about 5 to 8 mm should be immersed in the solution. A counter-electrode, either a piece of Pt foil or simply a piece of tungsten wire, can be a loop or simply a straight piece of foil or wire. It is essential that the tip specimen wire is held in the vertical position so that the convection of the solution during the polishing can be... 

All these observed features underline the fundamental importance of the adsorbate-induced surface structural transformations and can be qualitatively rationalized in terms of the outlined mechanism. For example, in order to obtain oscillations at given T and p0, the CO pressure (causing the respective CO coverage) must be high enough in order to lift the surface reconstruction, but, on the other hand, also sufficiently low to permit subsequently the reactive removal of the CO adlayer by oxygen. 

In [55] a large-area fabrication of hexagonally ordered metal dot arrays with an area density of 10u/cm2 was demonstrated. The metal dots were produced by an electron beam evaporation followed by a lift-off process. The dots size was 20 nm dots with a 40 nm period by combining block copolymer nanolithography and a trilayer resist technique. A self-assembled spherical-phase block copolymer top layer spontaneously generated the pattern, acting as a template. The pattern was first transferred to a silicon nitride middle layer by reactive ion etch, producing holes. The nitride layer was then used as a mask to further etch into a polyamide bottom layer. 

The use of the reactivity-selectivity descriptor Af(r) lifts the ambiguity. Figure 2 displays A/(r) for propene, it can be seen that the unsubstituted carbon of propene is a nucleophile (A/(r) < 0, yellow) that will react with an electrophile, the hydrogen of the halide. On the other hand, the substituted carbon is an electrophile (Af(r) > 0, red) and will react with the halide, as expected from the Markovnikov s rule. Discrimination between the nucleophilic and electrophilic power of the two carbons is very clear when using the reactivity-selectivity descriptor Af(r). 

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