High-Energy Photoemission at HASYLAB

An instrument for high‐energy X‐ray photoelectron spectroscopy is operated at the BW2 wiggler beamline of HASYLAB. The photon energy ranges from 2.3 to 10 keV, the electron energy reaches up to 7.5 keV (including an optional 2.5 keV sample bias, the current electron analyzer limit is 5 keV). Using a Si(311) double crystal monochromator, the total energy resolution is 0.37 eV at 4.3 keV as determined from the Si 2p photoemission. For Si(111) typical values are 0.45 eV at 3 keV. The photon flux typically amounts to 5×1012 1/s for Si(111). Focusing is achieved by the combination of a sagittally bent monochromator crystal and a tangentially bent mirror in the monochromatic beam. The focus size (FWHM) at the sample is 0.25 mm (vertical) × 2 mm (horizontal) which is well matching the acceptance of the SCIENTA SES‐200 electron analyzer. Selected results are shown to demonstrate the instrument performance.