An ultrahigh-vacuum apparatus for resonant diffraction experiments using soft x rays (hν=300–2000 eV).

We have developed an ultrahigh-vacuum instrument for resonant diffraction experiments using polarized soft x rays in the energy range of hν=300–2000 eV at beamline BL17SU of SPring-8. The diffractometer consists of modified differentially pumped rotary feedthroughs for θ-2θ stages, a sample manipulator with motor-controlled x-y-z-, tilt (χ)-, and azimuth ([lowercase_phi_synonym])-axes, and a liquid helium flow-type cryostat for temperature dependent measurements between 30 and 300 K. Test results indicate that the diffractometer exhibits high reproducibility (better than 0.001°) for a Bragg reflection of α-quartz 100 at a photon energy of hν=1950 eV. Typical off- and on-resonance Bragg reflections in the energy range of 530–1950 eV could be measured using the apparatus. The results show that x-ray diffraction experiments with energy-, azimuth-, and incident photon polarization-dependence can be reliably measured using soft x rays in the energy range of ∼300–2000 eV. The facility can be used for resonant diffraction experiments across the L-edge of transition metals, M-edge of lanthanides, and up to the Si K-edge of materials. [ABSTRACT FROM AUTHOR]