Christian Morawe

Upgraded ESRF BM29 beamline for SAXS on macromolecules in solution

A description of the new ESRF BioSAXS beamline is given. The beamline presented is dedicated to small-angle X-ray scattering of macromolecules in solution operating with a high-throughput sample-changer robot and automated data analysis for quality control and feedback.

The ID23-2 structural biology microfocus beamline at the ESRF

Beamline ID23-2, the first dedicated and highly automated high-throughput monochromatic macromolecular crystallography microfocus beamline, is described.

Efficient sub 100nm focusing of hard x rays

An x-ray beam with energy of 20.5keV has been efficiently focused down to a spot size as small as 90nm×90nm by a Kirkpatrick–Baez reflecting mirrors device. The first mirror, coated with a graded multilayer, plays both the role of vertical focusing device and monochromator, resulting in a very high flux (2×1011photons∕s) and medium monochromaticity (ΔE∕E∼10−2). Evaluation of the error contributions shows that the vertical focus is presently limited by the mirror figure errors, while the horizontal focus is limited by the horizontal extension of the x-ray source. With a gain in excess of a few million, this device opens up new possibilities in trace element nanoanalysis and fast projection microscopy.

Development of a new state-of-the-art beamline optimized for monochromatic single-crystal and powder X-ray diffraction under extreme conditions at the ESRF.

A new state-of-the art synchrotron beamline fully optimized for monochromatic X-ray diffraction at high pressure and high (or low) temperature is presented. In comparison with the old high-pressure beamline ID30, this new beamline exhibits outstanding performance in terms of photon flux and focusing capabilities. The main components of this new instrument will be described in detail and compared with the performance of beamline ID30. In particular, the choices in terms of X-ray source, X-ray optics, sample environment and detectors are discussed. The first results of the beamline commissioning are presented.

Design and fabrication of depth-graded X-ray multilayers

Abstract We present first experimental results on the fabrication and characterization of depth-graded X-ray multilayers providing a broad and well-defined reflectivity profile. Following a theoretical approach including analytical and numerical techniques we have designed and deposited multilayer structures with a practically constant reflectivity of about 20% around the first Bragg-reflection and a bandwidth of about 20% in both incident angle and photon energy. A precise characterization using numerical simulations allows the determination of residual errors in the structure, which can appear during or after the coating process. The discussion includes practical issues and technical limitations of the deposition process as well as novel applications in modern X-ray optics.

Dynamically-figured mirror system for high-energy nanofocusing at the ESRF

The design, manufacture and characterization of a Kirkpatrick-Baez (KB) configuration mirror system for high-throughput nanofocusing down to 50 nm beam sizes are described. To maximize the system aperture whilst retaining energy tunability, multilayer coated optics are used in conjunction with 2 dynamically figured mirror benders. This approach, which has been developed at the ESRF for many years, allows the focusing performance to be optimized when operating the system in the 13-25 keV photon energy range. Developments in the key technologies necessary for the production of mirror bending systems with dynamic figuring behavior close to the diffraction limit requirements are discussed. These include system optimization via finite element analysis (FEA) modeling of the mechanical behavior of the bender-mirror combination, manufacturing techniques for precisely-shaped multilayer substrates, multilayer deposition with steep lateral gradients and the stitching metrology techniques developed for the characterization and figure optimization of strongly aspherical surfaces. The mirror benders have been integrated into a compact and stable assembly designed for routine beamline operation and results of the initial performance of the system at the ESRF ID22NI endstation are presented demonstrating routine focusing of 17 keV X-rays to sub-60 nm resolution.

Nanofocusing at ESRF Using Graded Multilayer Mirrors

Dynamically bent graded multilayer mirrors have been developed at ESRF for their large energy bandwidth acceptance, energy tunability and large numerical aperture for limited mirror size. Kirkpatrick Baez systems with spot sizes below 100 nanometers have been installed on two beamlines. A diffraction limited line width of 41 nanometers FWHM was obtained at 24 keV on ID19. This experiment directly confirms that the penetration depth of the X‐rays in the multilayer coating does not limit the obtainable focal spot size. The resolution limits of such a nanofocusing device are discussed as well as figure accuracy and vibration level issues.

High-resolution multilayer x-ray optics

Presently there is a gap in energy resolution (Delta) E/E between a few percent for multilayer x-ray optics and a few 10-4 for perfect crystal optics. One approach to bridge this gap is the development of high-resolution multilayers. We will report on recent advances in this field and discuss both the capabilities and the limitations of this solution. The deposition of hundreds of layers of hard materials is a considerable challenge for the coating system, and stability issues have to be considered with particular care. We have shown theoretically and experimentally that this challenge can be met with a combination of Al2O3 and B4C. With 680 bilayers we reached a spectral resolution < 0.3% and a peak reflectivity of almost 50% for 12 keV x- rays. The disagreement with the diffraction properties of a perfect multilayer system could be accurately described by instabilities during the deposition process. With improved stability, such systems can provide still better performances.

The simultaneous measurement of energy and linear polarization of the scattered radiation in resonant inelastic soft x-ray scattering

Resonant Inelastic X-ray Scattering (RIXS) in the soft x-ray range is an element-specific energy-loss spectroscopy used to probe the electronic and magnetic excitations in strongly correlated solids. In the recent years, RIXS has been progressing very quickly in terms of energy resolution and understanding of the experimental results, but the interpretation of spectra could further improve, sometimes decisively, from a full knowledge of the polarization of incident and scattered photons. Here we present the first implementation, in a high resolution soft-RIXS spectrometer used to analyze the scattered radiation, of a device allowing the measurement of the degree of linear polarization. The system, based on a graded W/B4C multilayer mirror installed in proximity of the CCD detector, has been installed on the AXES spectrometer at the ESRF (European Synchrotron Radiation Facility); it has been fully characterized and it has been used for a demonstration experiment at the Cu L3 edge on a high-Tc superconducting cuprate. The loss in efficiency suffered by the spectrometer equipped with this test facility was a factor 17.5. We propose also a more advanced version, suitable for a routine use on the next generation of RIXS spectrometers and with an overall efficiency up to 10%.

Optical properties of boron carbide near the boron K edge evaluated by soft-x-ray reflectometry from a Ru/B 4 C multilayer

Soft-x-ray Bragg reflection from two Ru/B(4)C multilayers with 10 and 63 periods was used for independent determination of both real and imaginary parts of the refractive index n = 1 - delta + ibeta close to the boron K edge (approximately 188 eV). Prior to soft x-ray measurements, the structural parameters of the multilayers were determined by x-ray reflectometry using hard x rays. For the 63-period sample, the optical properties based on the predictions made for elemental boron major deviations were found close to the K edge of boron for the 10-period sample explained by chemical bonding of boron to B(4)C and various boron oxides.