Soft X-ray diffractometer for synchrotron radiation

Abstract

An ultra-high vacuum soft X-ray diffractometer has been constructed and commissioned at the Synchotron Radiation Research Center (SRRC) to investigate materials structures in mesoscale. The diffractometer, housed in a UHV tank, consists of a 6-circle goniometer, together with the systems for beam-collimation, signal detection, vacuum, and control panels. The κ– ϕ– ψ goniostat is adopted for the sample orientation. Crystal samples can be rotated along a given reciprocal lattice vector by using ψ scan. Two orthogonal axes, γ (or 2 θ) and δ, are used to move the detector. The detector is a semiconductor pin diode, which can be used in UHV ambient. This 6-circle goniometer allows for sample scanning of a wide range in the momentum space. The motors used for goniometer rotation and slit selection are UHV compatible. The UHV tank is placed on an XYZ table capable of positioning the center of the goniometer onto the incident beam. Test experiments have been carried on the 1–9 keV double-crystal monochromator (DCM) beamline to commission the diffractometer. These include powder diffraction of standard quartz crystals, θ–2 θ scans of zeolite thin films, specular reflectivity of Ti 2O 5/SiO 2/Zerdur multilayers, soft X-ray multiple diffraction of silicon single crystals, and the polarization effects on three-beam diffraction. The obtained experimental results demonstrate the excellent capability of the diffractometer in characterizing both mososcopic and microscopic structures of matter.