Dipoles, poling

Interactions between charges ion-ion, ionrdipole, and dipole- pole... 

Equation (6.13) shows the PU potential pick-up from the CC dipole. ri and F2 are the distance from the CC dipole to each of the PU dipole poles. In this way, the local electric field strength E [V/m] in the ri — T2 direction is measured. ri — F2 is actually the length of the PU dipole Lp . 

Figure 3.9. (a) Exciton coupling of two transitions localized in different parts of a molecule. The exciton splitting 2 Vy is a consequence of a dipole pole interaction, (b) The CD of the exciton transitions and the result of a superposition to a CD couplet. AAs is the amplitude of the couplet [48]. 

Other expressions for these so-called asymptotic intermolecular potentials are available for dipole pole cases, etc., including explicit orientation-dependent terms. A simple example is the interaction of an ion with a molecule that has a permanent dipole moment fj,. In this case, the induction energy (2.17) has an extra term, /z E, where E is the field of the ion, which is in the direction of the relative position vector R and the dot represents the scalar product of two vectors. Using the angle y between the permanent dipole and the relative separation ... 

As mentioned in the text and indicated in brackets, CO has a surprisingly reversed polarity compared to that expected from atomic electronegativity differences, but that is a question for another chapter.) The CO- -HF interaction might therefore be reasonably expected to epitomize the idealized limit of classical dipole pole forces. 

For this purpose, let us assume that the charge distributions belong to two bodies, which can be atoms or molecular units. By employing the quantum-mechanical correspondence principle, we replace the two-body potential (1.29) by an operator that acts in the combined state space of both bodies V(r) (ri, F2). We assume that the dipole pole interaction is weak compared with the individual energetic states of the bodies, i.e., we consider the dipole ipole operator//] as a perturbation, such that the Hamiltonian of the entire system can be written as... 

Note the r dependence of these tenns the charge-indiiced-dipole interaction varies as r, the dipole-indiiced-dipole as and the quadnipole-mduced-dipole as In general, the interaction between a pennanent 2 -pole moment and an induced I -pole moment varies as + L + l) gQ enough r, only the leading tenn is important, with higher tenns increasing in importance as r decreases. The induction forces are clearly nonadditive because a third molecule will induce another set of miiltipole moments in tlie first two, and these will then interact. Induction forces are almost never dominant since dispersion is usually more important. 

Molar absorptivity (Section 13 21) Ameasure of the intensity of a peak usually in UV VIS spectroscopy Molecular dipole moment (Section 1 11) The overall mea sured dipole moment of a molecule It can be calculated as the resultant (or vector sum) of all the individual bond di pole moments... 

A magnetic field exerts a force on each of the two poles of a dipole (particle), forcing it to ahgn itself with the hnes of magnetic force. 

For the reactions of other 1,3-dipoles, the catalyst-induced control of the enantio-selectivity is achieved by other principles. Both for the metal-catalyzed reactions of azomethine ylides, carbonyl ylides and nitrile oxides the catalyst is crucial for the in situ formation of the 1,3-dipole from a precursor. After formation the 1,3-di-pole is coordinated to the catalyst because of a favored chelation and/or stabiliza-... 

Zweiphasen-. (Elec.) two-phase, zwei-phasig, a. two-phase, diphase. -poUg, a. bipolar, dipole, double-pole, -quantig, a. of two quanta, 2-quantum. 

Naqvi [134] has proposed an alternative model to the Frye and Horst mechanism for the degradation and stabilization of PVC. At room temperature, PVC is well below its glass transition temperature (about 81°C). The low thermal stability of the polymer may be due to the presence of undesirable concentrations of like-poles in the more or less frozen matrix with strong dipoles. Such concentrations, randomly distributed in the polymer matrix, may be considered to constitute weak or high energy spots in the polymer, the possible sites of initiation of thermal dehydrochlorination. 

The symbols 5+ and 5- indicate polarity of the two ends or poles of the electrically neutral molecule. Such a polar molecule constitutes a permanent dipole, i.e., two equal and opposite charges (e) separated by a distance (d) in space. A quantitative measure of the polarity of a molecule is the dipole moment (p in Debye units), which is defined as the product of the charge (e in electrostatic units) and the distance (d in cm). 

Ihe arrow points toward the negative end of the polar bond (F atom) the plus sign is at the positive end (H atom). Ihe HF molecule is called a dipole it contains positive and negative poles. 

Polar molecules, like nonpolar molecules, are attracted to one another by dispersion forces. In addition, they experience dipole forces as illustrated in Figure 9.9, which shows the orientation of polar molecules, such as Id, in a crystal. Adjacent molecules line up so that the negative pole of one molecule (small Q atom) is as dose as possible to the positive pole (large I atom) of its neighbor. Under these conditions, there is an electrical attractive force, referred to as a dipole force, between adjacent polar molecules. 

Dipole Species in which there is a separation of charge, i.e., a positive pole at one point and a negative pole at a different point, 184,236... 

Polar molecule A molecule in which there is a separation of charge and hence positive and negative poles, 183-185 dipole force, 237 orientation, 183 Polarimeter, 600 Polarity, 184-185 Pollutants, 6 Polyamide, 615-616 Polyatomic ion, 36,39 Polyatomic molecules, 654 Polyester A large molecule made up of ester units, 614-615 Polyethylene, 611-612... 

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