Performance of the extreme-ultraviolet high-resolution undulator beamline BW3 at HASYLAB - first results and time-of-flight spectroscopy

The extreme ultraviolet beamline BW3 at Hasylab is a state of the art beamline for the energy range 15–2000 eV consisting of a triple undulator equipped with a modified high‐flux SX‐700 plane grating monochromator. The first three optical elements of the beamline are made of graphite coated with SiC to withstand the high heat load at the 4.5 GeV storage ring Doris III. Excellent spectral resolution of the order of 104 at the nitrogen K edge at 400 eV is obtained by replacing the elliptical focusing mirror of the original SX‐700 design by a spherical mirror with very small tangent errors and with a large focal length in order to suppress spherical aberrations. In the energy range 50–1700 eV a photon flux of 1011–1013/s is obtained in a bandpass of 0.1%. Photoionization and photoemission measurements on atoms, molecules, and clusters making use of time‐of‐flight techniques demonstrate the excellent performance of the beamline.