The properties of surface plasmons excited by electron tunneling near metallic structures with dimensions of a few hundred angstroms are examined. The excitations become localized by the microstructures, and the dependence of the dominant frequencies of these localized modes on junction geometry, material, and mode type is discussed. A calculation of the excited modes for thin rod microstructures is presented within an equivalent-circuit approximation. A complete calculation is given for surface plasmons localized by particles with curvature near the junction, including the radiation spectrum of the system. A distribution of particle microstructures is examined within an effective-medium theory. Comparison with experiments is made.

• Received 29 January 1981

DOI:https://doi.org/10.1103/PhysRevB.24.3276