Keesom interaction magnitude

D18.4 There are three van der Waals type interactions that depend upon distance as l/r6 they are the Keesom interaction between rotating permanent dipoles, the permanent-dipole-induced-dipole-interaction, and the induced-dipole-induced-dipole, or London dispersion, interaction. In each case, we can visualize the distance dependence of the potential energy as arising from the Mr dependence of the field (and hence the magnitude of the induced dipole) and the Mr3 dependence of the potential energy of interaction of the dipoles (either permanent or induced). 

Table 6 summarizes the radial dependence and the order of magnitude of the potential energy of the most common multipolar interactions distinguishing, for the dipole-dipole case, stationary molecules at a fixed distance r (as in solids) from rotating molecules (as in liquids and gases also called Keesom interactions). 

LW) interactions refer to the purely physical London s (dispersion), the Keesom s (polar) and Debye s (induced polar) interactions and correspond to magnitudes ranging from approximately 0.1 to 10 kJ/mol (but in rare cases may be higher). The polar forces in the bulk of condensed phases are believed to be small due to the self-cancellation occurring in the Boltzmann-averaging of the multi-body... 

Keesom forces are a function of the number and magnitude of a molecule s local dipole moments, but since they are dependent upon the positioning of a molecule with respect to its neighbors, they may not always be strictly additive. Flowever, since the molecules in most crystals are aligned for maximum dipolar interaction, the group interactions are often roughly additive. 

Polar forces between molecules in solution may arise from either permanent dipoles or Induced dipoles. When a molecule possessing a permanent dipole comes Into close association with a non-polar molecule, a relatively weak (0.0001 kcal/mole) permanent dipole-Induced dipole Interaction (Keesom force) arises. Close association of two permanent dipoles produces a stronger (1 to 2 kcal/mole) dipole-dipole Interaction or Debye force (12). In light of the relative magnitudes of these interactive forces, the Keesom forces and the extremely weak Induced dlpole-lnduced dipole Interactions will be omitted from further discussion. 

As we have seen, London dispersion interactions, Keesom dipole-dipole orientation interactions and Debye dipole-induced dipole interactions are collectively termed van der Waals interactions their attractive potentials vary with the inverse sixth power of the intermol-ecular distance which is a common property. To show the relative magnitudes of dispersion, polar and induction forces in polar molecules, similarly to Equation (78) for London Dispersion forces, we may say for Keesom dipole-orientation interactions for two dissimilar molecules using Equation (37) that... 

The thermodynamic model of adhesion, generally attributed to Sharpe and Schonhom [1], is certainly the most widely used approach in adhesion science nowadays. This theory considers that the adhesive will adhere to the substrate because of interatomic and intermolecular forces established at the interface, provided that an intimate contact between both materials is achieved. The most common interfacial forces result from van der Waals (London, Debye and Keesom) and Lewis acid-base interactions. The magnitude of these forces can generally be related to fundamental thermodynamic surface characteristics, such as surface free energies y, of both materials in contact. 

The surface free energy of a solid can be described as the sum of the dispersive and specific contributions. Dispersive (apolar) interactions, also known as Lifshitz-van der Waals interactions, consist of London interactions which originate from electron density changes but may include both Keesom and Debye interactions [6, 7]. Other forces influencing the magnitude of surface energy are Lewis acid-base interactions which are generated between an electron acceptor (acid) and an electron donor (base). Details of the widely accepted theoretical... 

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