Multipolar electromagnetic radiation

An oscillating electric dipole, localized at the origin of coordinates and represented by a three-dimensional delta-function in the xyz-space, radiates a classical electromagnetic (EM) field into its surrounding free space at its oscillation frequency ω. Combinations of delta-functions and their various derivatives with respect to x, y, and z can be similarly used to model electric as well as magnetic multipole radiators. We examine the emitted EM energy and angular momentum for several multipoles modeled by such localized oscillators. A quantum interpretation of these classical results can be loosely related to photoemission processes involving transitions between various electronic states of an atom or a molecule.