P04 is providing soft X-ray radiation with variable polarization to experiments at energies between 250 eV and 3 keV. The beamline offershigh energy resolution in the range from some tens of meV to about 1eV and high spatial resolution in the 10-µm regime. it is suited for new classes of experiments with soft x-rays in the fields of gas phase physics, gneticspectroscopy, high resolution photoelectron spectroscopy, surface chemistry, soft x-ray diffraction and holography.

The unique characteristics of this beamline are an exceptionally high photon flux – up to several 10E+12 photons per second – in a very small bandpass (resolving power exceeds 10,000) as well as variable polarization properties over a very wide energy range (200-3000 eV) using only the first harmonic of an APPLE-2 type undulator.

Due to the very low emittance of the PETRA III storage ring the radiation of the beamline is practically coherence limited in the whole photon energy range except for the horizontal source size (300 µm FWHM). The beam is supplied by a 5 m long APPLE-2-type undulator installed in one of the straight sections.