Quadrupole interaction, the interaction of systems of charged particles that is due to these systems having a quadrupole moment (see Quadrupole). If the electric charge or the dipole moment of the systems is other than zero, the quadrupole interaction can be neglected, because in order of magnitude it is considerably smaller than the electrostatic and dipole interactions.
The quadrupole interaction matters for the interaction of atoms at large distances, if the quadrupole moment of both atoms is other than zero. The energy of the quadrupole interaction of atoms (which have no electric dipole moment) falls off as the distance R increases, in proportion to 1/R5, whereas the energy of the interaction of the dipole moments induced in these atoms by their mutual polarisability varies with distance in proportion to 1/R8. The quadrupole interaction of atoms at large distances therefore proves to be the dominant one. The quadrupole moments of atoms can be calculated by the methods of quantum mechanics.
Many atomic nuclei have a quadrupole moment, the distribution of electric charge in them having no spherical symmetry (see Nuclear quadrupole moment). The quadrupole interaction plays a large part in nuclear physics in the excitation of nuclei with zero dipole moment by the Coulomb field of charged particles incident on the nuclei.
The quadrupole interaction matters for the interaction of atoms at large distances, if the quadrupole moment of both atoms is other than zero. The energy of the quadrupole interaction of atoms (which have no electric dipole moment) falls off as the distance R increases, in proportion to 1/R5, whereas the energy of the interaction of the dipole moments induced in these atoms by their mutual polarisability varies with distance in proportion to 1/R8. The quadrupole interaction of atoms at large distances therefore proves to be the dominant one. The quadrupole moments of atoms can be calculated by the methods of quantum mechanics.
Many atomic nuclei have a quadrupole moment, the distribution of electric charge in them having no spherical symmetry (see Nuclear quadrupole moment). The quadrupole interaction plays a large part in nuclear physics in the excitation of nuclei with zero dipole moment by the Coulomb field of charged particles incident on the nuclei.