  We consider exciton optical absorption in quasiperiodic lattices, focusing
our attention on the Fibonacci case as typical example. The absorption spectrum
is evaluated by solving numerically the equation of motion of the
Frenkel-exciton problem on the lattice, in which on-site energies take on two
values according to the Fibonacci sequence. We find that the quasiperiodic
order causes the occurrence of well-defined characteristic features in the
absorption spectra. We also develop an analytical method that relates satellite
lines with the Fourier pattern of the lattice. Our predictions can be used to
determine experimentally the long-range quasiperiodic order from optical
measurements.
