A novel monochromator for experiments with ultrashort X-ray pulses

作者：Brzhezinskaya Maria; Firsov Alexander; Holldack Karsten^*; Kachel Torsten; Mitzner Rolf; Pontius Niko; Schmidt Jan Simon; Sperling Mike; Stamm Christian; Foehlisch Alexander; Erko Alexei

来源：Journal of Synchrotron Radiation, 2013, 20(4): 522-530.

DOI：10.1107/S0909049513008613

• femtosecond X-ray pulses
• storage ring
• elliptical undulators
• slicing
• diffractive optics
• reflection zone plates
• time-resolved X-ray spectroscopy

Aiming at advancing storage-ring-based ultrafast X-ray science, over the past few years many upgrades have been undertaken to continue improving beamline performance and photon flux at the Femtoslicing facility at BESSY II. In this article the particular design upgrade of one of the key optical components, the zone-plate monochromator (ZPM) beamline, is reported. The beamline is devoted to optical pump/soft X-ray probe applications with 100 fs (FWHM) X-ray pulses in the soft X-ray range at variable polarization. A novel approach consisting of an array of nine off-axis reflection zone plates is used for a gapless coverage of the spectral range between 410 and 1333 eV at a designed resolution of E/Delta E = 500 and a pulse elongation of only 30 fs. With the upgrade of the ZPM the following was achieved: a smaller focus, an improved spectral resolution and bandwidth as well as excellent long-term stability. The beamline will enable a new class of ultrafast applications with variable optical excitation wavelength and variable polarization.

• 出版日期2013-7