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Magnetic dipole–dipole interaction, also called dipolar coupling, refers to the direct interaction between two magnetic dipoles. Roughly speaking, the magnetic field of a dipole goes as the inverse cube of the distance, and the force of its magnetic field on another dipole goes as the first derivative of the magnetic field. It follows that ...
It is related to the prototypical Ising model, where at each site of a lattice, a spin {} represents a microscopic magnetic dipole to which the magnetic moment is either up or down. Except the coupling between magnetic dipole moments, there is also a multipolar version of Heisenberg model called the multipolar exchange interaction .
For a fully oriented molecule, the dipolar coupling for an 1 H-15 N amide group would be over 20 kHz, and a pair of protons separated by 5 Å would have up to ~1 kHz coupling. However the degree of alignment achieved by applying magnetic field is so low that the largest 1 H- 15 N or 1 H- 13 C dipolar couplings are <5 Hz. [ 19 ]
More specifically, we shall derive an analytical expression for the strength of the inter-dot Foerster coupling. It can be also shown that this coupling is, under certain conditions, of dipole-dipole type and that it is responsible for resonant exciton exchange between adjacent QD's. This is a transfer of energy only, not a tunnelling effect.
By truncating this expansion (for example, retaining only the dipole terms, or only the dipole and quadrupole terms, or etc.), the results of the previous section are regained. In particular, truncating the expansion at the dipole term, the result is indistinguishable from the polarization density generated by a uniform dipole moment confined ...
The dipole has a low-lying LUMO which overlaps with HOMO of the dipolarophile (indicated by red dashed lines in the diagram). A dipole of this class is referred to as a LUMO-controlled dipole or an electrophilic dipole, which includes nitrous oxide and ozone. EWGs on the dipolarophile decelerate the reaction, while EDGs accelerate the reaction.
A key example of this phenomenon is the spin–orbit interaction leading to shifts in an electron's atomic energy levels, due to electromagnetic interaction between the electron's magnetic dipole, its orbital motion, and the electrostatic field of the positively charged nucleus.
An example of a dipole–dipole interaction can be seen in hydrogen chloride (HCl): the positive end of a polar molecule will attract the negative end of the other molecule and influence its position. Polar molecules have a net attraction between them. Examples of polar molecules include hydrogen chloride (HCl) and chloroform (CHCl 3).