High-intensity x-ray microbeam for macromolecular crystallography using silicon kinoform diffractive lenses.

Macromolecular crystallography often requires focused high-intensity x-ray beams for solving challenging protein structures from micrometer-sized crystals using current synchrotron radiation sources. The design of optical focusing schemes for hard x-rays showing high efficiency and flexibility in beam size is therefore continuously pursued. Here, we present an innovative solution based on a two-stage demagnification of the undulator source for photon energies from 6 keV to 19 keV, commissioned at the X10SA beamline of the Swiss Light Source, where a secondary source is imaged by two crossed silicon kinoform x-ray diffractive lenses with 75 nm outermost zone width. A source-size limited spot with a size of 4.8  μm×1.7  μm(h×v,FWHM) and flux of 7.5×10  photons/s at 12.4 keV is demonstrated at the sample position.