A compact double crystal monochromator for electrochemistry beamline at PLS

A compact double crystal monochromator based on 16.5′′ CF flange has been designed, fabricated and installed for electrochemistry beamline at Pohang light source. The Bragg angle range of the monochromator is 7–75°. The mechanical design is modified from typical Boomerang design [J.A. Golovchenko et al., Rev. Sci. Instrum. 52 (1981) 509; J.P. Kirkland, Nucl. Instr. and Meth. A291 (1990) 185] to have fixed beam offset and single driving axis for spectroscopy experiments. The parallelism error of the crystals is minimized to less than 6μrad for the range, by using a precision single axis linear guide, Also, the number of mechanical parts in the vacuum is minimized and 1.8×10−9Torr of vacuum is achieved without baking.