Determination of multilayer structure was developed so much, but most of studies focused on the relationship between structural imperfections and reflectivity. These imperfections, whether interfacial roughness and interdiffusion or surface feature, measured by grazing X-ray scattering, atomic force microscopy or electric microscopy, reflect relatively high-frequency characteristics. The mid-frequency figure errors were regarded as the main factor to produce large satellite peaks near the focusing spot in the multilayer K-B mirror and were found to produce stripes in the far-field imaging. We report novel method to study mid-frequency interface and layer growth characterizations of multilayer structure using at-wavelength speckle scanning technique. This work is beneficial for matching multilayer manufacture technology to the optimization of beam performances.
The hard X-ray nanoprobe beamline (HXN) designed at the Shanghai Synchrotron Radiation facility (SSRF) will be of capability to realize a focal spot size of 10 nm for hard X-rays to satisfy requirements in biology, environmental, material sciences and etc.. The beamline includes two modes of operation, high energy resolution mode and high flux mode respectively. High flux mode utilizes the multilayer KB system to obtain high-flux diffraction-limited focusing of ~10nm. An ultra-high-precision figure fabrication for diffraction-limited focusing is required to meet the Rayleigh Criterion. An idea to overcome this problem is to introduce a phase compensator upstream of the KB system to compensate the wavefront errors in the beamline. At wavelength speckle-based method will be used to measure the wavefront error in the beamline and feedback to the phase compensator. Vibration measurements have been carried out at the secondary source and endstation hutch. The flexure hinge mechanisms and high-precision actuators ensure the KB system and sample manipulator working with high stability. The building of HXN has been designed and is under construction at present.
Multilayer monochromators are widely needed in synchrotron beamlines to provide the high photon flux as compared to
crystals. Ru/B4C multilayer is the most promising candidate working at the energy region of 10-20 keV. To develop this
multilayer monochromator for an undulator beamline with high power density, the layer structure and reflectivity of the
multilayer were studied. The deposition process for the Ru/B4C multilayers was first optimized. Multilayers with
different periods (d=2.0 nm, 3.0 nm, 4.0 nm) and single layers fo Ru and B4C were fabricated and characterized using
the grazing incidence X-ray reflectometry (GIXR). A low density of Ru in the multilayers was found as compared to the
single layers which attributed to the relatively low reflectance of 53.3% at 8.05 keV of the multilayer with 3.0 nm period.