Repulsive range

AEba = —45 kJ mol 1 for the HO + SiH4 reaction and AEba = —43 kJ mol-1 in the reaction of hydrogen atom with water. The repulsion of the electron orbitals of the atoms forming the reaction center AER plays an important role in all the radical abstraction reactions. In the interaction of radicals with molecules the contribution of this repulsion ranges from 25 to 46 kJ mol-1. In reactions of molecules with hydrogen atoms the contribution is naturally smaller, varying from 8 to 16kJ mol-1. 

Malescio G., Franzese G., Skibinsky A., Buldyrev S., Stanley H. (2005) Liquid-liquid phase transition for an attractive isotropic potential with wide repulsive range, Phys. Rev. E, 71(6), 061504-061512. 

In the physics literature, the model invented to go beyond the severely truncated electron-repulsion range of the Hubbard model has been the extended Hubbard Hamiltonian or the U-V model. Here, the intersite interactions are introduced between bonded sites through another independent phenomenological interaction parameter V [26] from which the model derives its name. The Hamiltonian is given... 

Figure 9.7. The effect of particle size and the repulsive range on the particle packing density. (From ref. (15) with permission of The American Ceramic Society)...

The second factor to influence fine particle and colloidal suspension rheology is the interaction force between the particles. (The first factor being the volume fraction of particles.) The sense (attractive or repulsive), range and magnitude of the surface forces all influence the suspension rheological behaviour. 

TABLE 21.6 Madelnngconstants and repulsive range parameters of some ionic crystals... 

The lattice energy for potassium iodide, Kl, is 627.2 kJ/mol. If the ionic separation is 3.533 A, what is the repulsive range parameter p for Kl You will have to determine which Madelung constant to use. 

We now come to the effect of temperature on F(D) curves. It can be seen in Figure 3.5 that, as the temperature is increased, the onset of repulsive forces occurs at smaller intersurface separations (Figure 3.5a,b), and that hard wall repulsion, i.e., a situation of quasi-fully compressed brushes, occurs at lower normal forces. Such a temperature dependence of the repulsive range shows that the thickness of the brushes indeed decreases as the temperature is increased grafted chains go from a low-temperature swollen state to a high-temperature collapsed state where most of the solvent is... 

Contact mode AFM. This measures the sample topography by sliding the probe tip across the sample surface. The tip-sample distance is maintained within the repulsive range of the atomic forces. 

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