Strongly localized plasmon oscillations in a cluster of two metallic nanospheres and their influence on spontaneous emission of an atom

The plasmon oscillations in a cluster of two nearly touching metallic nanospheres are studied. Simple analytical expressions have been found for the spectra of plasmon oscillations of different symmetry. A type of plasmon oscillations (plasmonic molecule) which are strongly localized between the spheres and which totally disappear at separation of the spheres has been discovered. The plasmon oscillations found have a dramatic effect on the optical properties of an atom localized between the spheres.