Charge-induced dipole interactions

Electrostatic interactions encompass ionic, dipole-t ii ., dipole-induced dipole, or charge-induced dipole interactions. No fo-aial elaboration of the appropriate equations will be given here becujis the alkyl bonded stationary phases most commonly used in RPC are no, expected... 

Both the n independence and the 1/v dependence of the cross section agree with a description based on the perturber s scattering from the Li+ core. Since the electron is not involved, the cross section is n independent, and the charge-induced dipole interaction leads to a 1/v dependence of the cross section. Furthermore, the measured rate constants are in good agreement with those computed for the scattering of Li+ from the perturbers, as shown in Table 11.2. 

The induced dipole moment depends on the electric field strength and the structure of the molecule. Charge-induced dipole interactions occur between a charged ion and polarized molecules. A molecule possessing conjugated double bonds is readily polarized. Examples of solutions due to the dipole-induced dipole interaction are benzene in methanol, chloral hydrate in CC14, and phenol in mineral oil. 

If the molecule is an ion bearing a charge Qj, then the leading induction term is the isotropic, charge-induced-dipole interaction... 

Note the r dependence of these terms the charge-induced-dipole interaction varies as r, the dipole-induced-dipole as r ° and the quadrupole-induced-dipole as r. In general, the interaction between a permanent 2 -pole moment and an induced 2 -pole moment varies as At large enough r, only the leading term is important, with higher terms increasing in importance as r decreases. The induction forces are clearly nonadditive because a third molecule will induce another set of multipole moments in the first two, and these will then interact. Induction forces are almost never dominant since dispersion is usually more important. 

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