  A hitherto unexplored method for the experimental determination of the photon
strength function up to the neutron separation energy was developed at the
Radiation Source ELBE in Dresden. It was applied to various heavy nuclei,
preferentially to nuclides with increasing distance to the N=50 neutron shell,
and it covers the high level density excitation energy range above 4 MeV. The
observed quasi-continuous spectra of scattered photons can be -- after a proper
correction for multi-step processes -- directly combined to nuclear photo
effect data from literature. A remarkably good match of the photon strengths as
measured below and above the neutron emission threshold is observed. The wide
energy coverage of the combined data forms an excellent basis to derive a
parameterization for the dipole strength function fully covering the range
across the nucleon separation energies. In addition to the parameters defining
the deformation of the nuclear ground states only one additional constant is
needed to describe the dipole strength in the nuclei with 88<A<116. The new
parameterization differs significantly from the prescriptions generally used in
network calculations, e.g. those of interest for the cosmic nucleo-synthesis.
