Extreme X-ray beam compression for a high-resolution table-top grazing-incidence small-angle X-ray scattering setup

The application of V-shaped channel-cut GeSi(220) and Ge(220) monochro-mators for one-dimensional extreme X-ray beam compression was tested on atable-top setup for grazing-incidence small-angle X-ray scattering (GISAXS)with a microfocus source. A lattice constant gradient and different asymmetryangles of the diffractors were employed to enhance the compression factorto 21and 15, respectively. It was demonstrated that the output beam parameters interms of the size, divergence, photon flux and spectral bandwidth surpass thoseof the slit collimators used traditionally in GISAXS. A beam size far below100 mm allows a high-resolution spatial GISAXS mapping, while the reciprocalspace resolution of 500 nmapproaches the level ofsynchrotron measurementsand allows a fast one-shot detection of high-resolution GISAXS patterns. Anoversamplingshiftsthedetectionlimitupto 1 mm.Theveryshortdesignofthecompact high-resolution table-top GISAXS setup is another advantage of theextremebeamcompression.BenefitsofV-shapedmonochromatorsformedium-resolution X-ray diffraction experiments as a bonus application are demon-strated by a comparison with parallel channel-cut monochromators combinedwith a slit.1. IntroductionIncreasing demand for dedicated structural characterizationfacilities triggered by progress in materials science, nano-technologies and other fields has stimulated new develop-ments in X-ray instrumentation. Microfocus X-ray sourceswithbuilt-inreflectiveopticsareatypicalexampleofadvancesthat have allowed some experiments to be moved fromsynchrotron to laboratory and that have enhanced throughputof laboratory measurements. In particular, grazing-incidencesmall-angle X-ray scattering (GISAXS) is a unique techniquefor nondestructive characterization of nanostructures and insitu probing of processes at the nanoscale, which is applicablein diverse fields of science (Renaud et al., 2003, 2009; Mu¨ller-Buschbaum et al., 2007). Commercial table-top SAXS andGISAXS setups with a microfocus X-ray source are availablenowadays. Here, traditional schemes for shaping a narrowcollimated beam such as a slit collimator or a modified Kratkycamera cannot provide effective collection of the sourceintensity and cause a considerable intensity loss. While this isnot so much an issue for synchrotron measurements, it iscrucial for laboratory setups. New solutions for beam condi-tioning are urgently needed to fully utilize the potential of thelaboratory microfocus X-ray sources.Asymmetric X-ray diffraction offers the possibility of beamfootprint control (compression or expansion) depending onthe asymmetry angle and the Bragg angle