dipole-dipole interaction

Dipole-dipole interaction

The interaction of two atoms, molecules, or nuclei by means of their electric or magnetic dipole moments. This is the first term of the multipole-multipole series of invariants. More precisely, the interaction occurs when one dipole is placed in the field of another dipole. The interaction energy depends on the strength and relative orientation of the two dipoles, as well as on the distance between the centers and the orientation of the radius vector connecting the centers with respect to the dipole vectors. The electric dipole-dipole interaction and magnetic dipole-dipole interaction must be distinguished.

The center of the negative charge distribution of a molecule may fail to coincide with its center of gravity, thus creating a dipole moment. An example is the water molecule. If such molecules are close together, there will be a (electric) dipole-dipole interaction between them. Atoms do not have permanent dipole moments, but a dipole moment may be induced by the presence of another atom nearby; this is called the induced dipole-dipole interaction. Induced dipole-dipole forces between atoms and molecules are known by many different names: van der Waals forces, London forces, or dispersion forces. These induced dipole-dipole forces are responsible for cohesion and surface tension in liquids. They also act between unlike molecules, resulting in the adsorption of atoms on macroscopic objects. See Cohesion (physics), Intermolecular forces, Van der Waals equation

The magnetic dipole-dipole interaction is found both on a macroscopic and on a microscopic scale. Two compass needles within reasonable proximity of each other illustrate clearly the influence of the dipole-dipole interaction. In quantum mechanics, the magnetic moment is partially due to a current arising from the motion of the electrons in their orbits, and partially due to the intrinsic moment of the spin. The same interaction exists between nuclear spins. Magnetic dipole-dipole forces are particularly important in low-temperature solid-state physics, the interaction between the spins of the ions in paramagnetic salts being a crucial element in the use of such salts as thermometers and as cooling substances. See Adiabatic demagnetization, Dipole, Electron, Low-temperature thermometry, Magnet, Magnetic thermometer, Nuclear moments

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.

dipole-dipole interaction

[¦dī‚pōl ¦dī‚pōl ‚in·tər ′ak·shən]
(atomic physics)
The interaction of two atoms, molecules, or nuclei by means of their electric or magnetic dipole moments. The interaction energy depends on the strength and relative orientation of the two dipoles, as well as on the distance between the centers and the orientation of the radius vector connecting the centers with respect to the dipole vectors.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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References in periodicals archive ?
It is important to note that solubility parameter does not take into account secondary forces in polymers like dipole-dipole interaction and hydrogen bonding.
Properties like increased strength in the bromocyclopentane is imparted by the strong intermolecular forces, the magnitude of the forces is the resultant of high dipole-dipole interaction. Also due to the availability of less number of carbon hydrogen bond the bromocyclopentane shows less flammability than its corresponding alkane.
Note that the acidity of both analyte and silanol group and thus the dipole-dipole interaction are enhanced in acetonitrile [18].
This significant deviation from unity in the ([g.sub.f]) values of the studied systems confirms that the effective dipoles in the mixture will be less than the corresponding average value in pure liquids and the clustering due to dipole-dipole interaction between the two hetero molecules.
In this work, a numerical method for computing the dynamics of the two-component dipolar BEC is considered, where one equation has dipole-dipole interaction and the other has only the usual s-wave contact interaction.
This fact allows us to conclude that there is no dipole-dipole interaction between stabilized electrons and [Mo.sup.5+] centres in the heteropolyacid anion, which means that the distance between the neighbouring paramagnetic centres is larger than 2.5-3 nm.
He showed that the electrostatic interaction between charged interfacial colloidal particles is dominated by the screened-Coulomb contribution, which decays exponentially at small separations and by an algebraic dipole-dipole interaction at large separations:
The strength of this magnetic dipole-dipole interaction is comparable to the neutron-nuclear interaction, and thus there are magnetic cross-sections that are analogous to the nuclear ones that reveal the complete structure and full range of lattice dynamics of materials over wide ranges of length scale and energy.
Also, from the technological point of view of modern thin-film magnetic devices, a visual real method to illustrate the formation of stable long-range magnetic order in the quasi-two-dimensional systems of magnetic dipoles is needed due to the difficulty in integrating the long-range dipole-dipole interaction in quasi-two-dimensional systems.
The contribution to the electric field at position i due to the dipole at position j is contained in the second term on the right side of (2) and is normally expressed in terms of the dipole-dipole interaction matrix A as