  The recently discovered enhancement of eta photoproduction on the quasi-free
neutron at energies around sqrt(s)~1.67 GeV is addressed within a SU(3) coupled
channel model. The quasi-free cross sections on proton and neutron, sigma_n and
sigma_p, can be quantitatively explained. In this study, the main source for
the peak in sigma_n/sigma_p is a coupled channel effect in S-wave that explains
the dip-bump structure in gamma n --> eta n. In particular, the photon coupling
to the intermediate meson-baryon states is important. The stability of the
result is extensively tested and consistency with several pion- and
photon-induced reactions is ensured.
