  The spin echo approach is extended to include bio-complexes for which the
interaction with dynamical noise is strong. Significant restoration of the free
induction decay signal due to homogeneous (decoherence) and inhomogeneous
(dephasing) broadening is demonstrated analytically and numerically, for both
an individual dimer of interacting chlorophylls and for an ensemble of dimers.
This approach is based on an exact and closed system of ordinary differential
equations that can be easily solved for a wide range of parameters that are
relevant for bio-applications.
