  Optical absorption in a random one-dimensional lattice in the presence of
paired correlated disorder is studied. The absorption line shape is evaluated
by solving the microscopic equations of motion of the Frenkel-exciton problem
in the lattice. We find that paired correlation causes the occurrence of
well-defined characteristic lines in the absorption spectra which clearly
differ from the case of unpaired correlation. The behavior of the absorption
lines as a function of defect concentration is studied in detail. We also show
how exciton dynamics can be inferred from experimental data by deriving an
analytical expression relating the energy and intensity of lines to the model
parameters.
