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].