Optical surface modes in a system of fine metallic particles

The interaction of electromagnetic radiation with a low-density disordered system of fine metallic particles located in a dielectric matrix is conside red in a quasi-static approach with allowance for dipole-dipole interaction . The electric dipole moment of the system is calculated in a pair approxim ation. The case of nonidentical particles differing in their sizes or diele ctric functions is presented. Allowance for particle nonidentity leads to d oubling of the number of their surface modes and to the appearance of band gaps in the spectrum. The spectrum peculiarities are revealed in the fine s tructure of electromagnetic absorption. (C) 1999 American Institute of Phys ics. [S1063-777X(99)01110-X].