The dipole response of neutron-rich oxygen nuclei O17-22 has been studied u
sing the electromagnetic excitation process in heavy ion collisions at beam
energies around 600 MeV/nucleon. The subsequent neutron decay after inelas
tic scattering of tile secondary beam projectiles on a Pb target was measur
ed in a kinematically complete experiment. Differential electromagnetic exc
itation cross sections were deduced up to 30 MeV excitation energy. For all
isotopes low-lying El strength was obtained exhausting between 5% and 12%
of the energy-weighted dipole sum rule.