Self ions

We also synthesised the salt AlTf2SbF and found its activity even more pronounced than that of the most efficient perchlorates. Almost explosive polymerisations were observed with most monomers tried in nitromethane. This salt does not need to self-ion-ise in solution since it is ionic in the solid state and can be considered the equivalent of such carbocationic salts as Ph3C SbFg and tropylium hexafluorophosphate. We expect therefore that its initiation interaction with olefins follows a simple 1 1 addition. 

In a sample of pure water, the concentration of hydronium ions is equal to 1X10 moles per liter (0.0000001 M). The equilibrium (balance) between hydronium and hydroxide ions that results from self-ion-ization of water can be disturbed if other substances that can donate protons are put into solution with water. 

Fig. 7.3. The fraction of the PKA energy deposited in atomic collisions (damage efficiency, v(E)IE) as a function of PKA energy and self-ion type. Here we define the PKA energy as E (after Robinson 1965)...

Black-white contrast of dislocation loops under dynamical two-beam imaging conditions. The figure shows the same area of a Cu specimen, containing small dislocation loops formed by irradiation with 30keV self ions. The g-vectors are (a) (111) and (b) (111). ... 

Do calculations using the concept of the self-ion izaton of water. (Section 9.4)... 

The relative stability of V2 < 111 > and < 100> dislocation loops in pure Fe and bcc Fe-Cr alloys was determined as a function of temperature under Fe self-ion irradiation [8]. Fig. 7.4 shows the fraction of two types of dislocation loops as a function of irradiation temperature. For pure iron, the microstmeture was dominated by V2 < 111 > interstitial loops at temperatures < 300°C, although small < 100> loops were still present even at room temperature. At temperatures Tin > 400°C, <100> loops became more dominant than V2 <111> loops. At temperatures Tin- > 450°C, small, mobile V2 <111> loops were subsumed by sessile <100> loops and large V2 <111> loops were not observed. At 500°C, <100> loops developed into large networks, and no visible V2 <111> loop formed [8]. 

Composition can affect the types of loops formed under radiation. In Fe-Cr alloys, the damage structures as a function of temperature are basically similar to those in pure Fe under Fe self-ion irradiation, but the loop size in Fe-Cr alloys is much smaller than that in pure Fe [14]. Moreover, the proportions of two loop types in Fe-Cr alloys are also affected by the alloy composition [15]. The fraction of V2 <111> loops increases with Cr content after neutron irradiation at 400—450°C to 15 dpa [16,17]. <100> dislocation loops were predominant in the microstructure in Fe-Cr alloys with Cr content less than 6% and a mixed <100> and V2 <111> loops formed in Fe-Cr alloys with higher Cr content under neutron irradiation at 400°C [15]. In addition, the presence of Cr in a Fe-Cr binary alloy can remarkably decrease the size of the interstitial loops after neutron irradiation [11,18]. The ratio and size of V2 <111> and <100> dislocations and/or dislocation loops have some effects (although moderate) on radiation hardening because higher mobility of V2 < 111 > dislocation loops could result in their almost complete disappearance via annihilation at the surface. In Fe-Cr alloys, the suppression of mobility of interstitial defects by Cr atoms results in a higher recombination rate and leads to delays in the formation of visible defects [10,11]. Similar effects on loop size and type may also come from other constituent elements, such as Ni as well as interstitial atoms such as C and N [19]. 

The use of high energy ions of the condensable him materials (him ions, self ions) is a special case where the deposihng and bombarding species are the same. The advantage is that, since... 

O.V Kononenko, VN. Matveev, N.A. Kislov, I.I. Khodos, A.Y. Kasumov, The effect of self-ions bombardment on the structure and properties of thin metal films. Vacuum 46 (7) (1995) 685. 

Self-ion An ion of the vaporized material that can bombard the target on growing film, giving Self-sputtering. See also Film Ion. 

Self-sputtering Sputtering by an ion of the target material being sputtered (Self-ion). See also Film ion. 

The field ion microscope (FIM) has been used to monitor surface self-diflfiision in real time. In the FIM, a sharp, crystalline tip is placed in a large electric field in a chamber filled with Fie gas [14]. At the tip. Fie ions are fonned, and then accelerated away from the tip. The angular distribution of the Fie ions provides a picture of the atoms at the tip with atomic resolution. In these images, it has been possible to monitor the diflfiision of a single adatom on a surface in real time [15]. The limitations of FIM, however, include its applicability only to metals, and the fact that the surfaces are limited to those that exist on a sharp tip, i.e. difhision along a large... 

The power of optical spectroscopies is that they are often much better developed than their electron-, ion- and atom-based counterparts, and therefore provide results that are easier to interpret. Furtlienuore, photon-based teclmiques are uniquely poised to help in the characterization of liquid-liquid, liquid-solid and even solid-solid interfaces generally inaccessible by other means. There has certainly been a renewed interest in the use of optical spectroscopies for the study of more realistic systems such as catalysts, adsorbates, emulsions, surfactants, self-assembled layers, etc. 

Using as many methods as are available to you for comparison (Mathcad, QBASIC, and TRUE BASIC), determine the self-consistent field (SCF) energies of the He atom and of the ions Li+, Be " ", and B +. Fill in the SCF column of Table 8-1. 

The Raman spectrum of nitric acid shows two weak bands at 1050 and 1400 cm. By comparison with the spectra of isolated nitronium salts ( 2.3.1), these bonds were attributed to the nitrate and nitronium ion respectively. Solutions of dinitrogen pentoxide in nitric acid show these bands , but not those characteristic of the covalent anhydride , indicating that the self-dehydration of nitric acid does not lead to molecular dinitrogen pentoxide. Later work on the Raman spectrum indicates that at —15 °C the concentrations of nitrate and nitronium ion are 0-37 mol 1 and 0 34 mol 1 , respectively. The infra-red spectrum of nitric acid shows absorption bands characteristic of the nitronium ion. The equivalence of the concentrations of nitronium and nitrate ions argues against the importance of the following equilibrium ... 

The nitronium ions produced in this way tend to repress the selfdehydration of the nitric acid and therefore the net concentration of nitronium ions is not proportional to the concentration of the catalyst. When sufficient sulphuric acid has been added to make the self-ioniza-tion of nitric acid relatively unimportant, the nitronium ions will be produced predominantly from the above ionization, and the acceleration will follow a linear law. 

If we consider the effect of nitrous acid upon zeroth-order nitration in organic solvents we must bear in mind that in these circumstances dinitrogen tetroxide is not much ionised, so the measured concentration of nitrous acid gives to a close approximation the concentration of dinitrogen tetroxide. Further, the negligible self-ionisation of nitric acid ensures that the total concentration of nitrate ions is effectively that formed from dinitrogen tetroxide. Consequently as we can see from the equation for the ionisation of dinitrogen tetroxide ( 4.3.1),... 

In practice this reaction is difficult to carry out with simple aldehydes and ketones because aldol condensation competes with alkylation Furthermore it is not always possi ble to limit the reaction to the introduction of a single alkyl group The most successful alkylation procedures use p diketones as starting materials Because they are relatively acidic p diketones can be converted quantitatively to their enolate ions by weak bases and do not self condense Ideally the alkyl halide should be a methyl or primary alkyl halide... 

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