Charge site energy

The three p orbitals are directed along the three cartesian axes and so, in an octahedral crystal field, suffer equal repulsion from point charges sited on those axes. The energies of the three p orbitals, therefore, remain degenerate. Similarly, a free-ion P term remains unsplit in octahedral or tetrahedral crystal fields and is labelled Tig or Ti respectively. 

In a multi-molecular system with Nmoiec molecules and each molecule consisting of Natom atoms and Nsite charged sites, the total energy becomes... 

If fluctuations in the intermolecular distances and orientations give rise to a large variation in the site energy and transition probability amplitude compared to the other terms, the static disorder dominates the charge transport. A charge carrier moves by uncorrelated hops in a broad density of states. Thermal activation is required to overcome the energy differences between different sites. 

Distonic ions reacting primarily at the radical center provide the opportunity to study free radical reactions in the gas phase by MS. For example, 4-dehydroanilin-ium ions (37 +, m/z = 93) were generated by multiple low-energy collisions of chloro-, bromo-, or iodoanilinium ions (36+, m/z = 220) with argon. This distonic species reacted with dimethyl sulfide by abstraction of thiomethyl (MeS ), that is, as a reactive radical with an inert charge site. However, 37 + can be deprotonated by pyridine. 2° ... 

Practical applications of surfactants usually involve some manner of surfactant adsorption on a solid surface. This adsorption is always associated with a decrease in free-surface energy, the magnitude of which must be determined indirectly. The force with which the adsorbate is held on the adsorbent may be roughly classified as physical, ionic, or chemical. Physical adsorption is a weak attraction caused primarily by van der Waals forces. Ionic adsorption occurs between charged sites on the substrate and oppositely charged surfactant ions, and is usually a strong attractive force. The term chemisorption is applied when the adsorbate is joined to the adsorbent by covalent bonds or forces of comparable strength. 

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