Jörg Wiesmann

Improved analyzer multilayers for aluminium and boron detection with x-ray fluorescence

We have developed improved analyzer multilayers for the detection of aluminium (Al) and boron (B) on silicon (Si) wafers with wavelength-dispersive x-ray fluorescence spectrometers. For the detection of Al on Si wafers we show that WSi(2)/Si and Ta/Si multilayers provide detection limits that are 42% and 60% better, respectively, than with currently used W/Si multilayers. For the detection of B on Si wafers we show that La/B(4)C multilayers improve the detection limit by approximately 28% compared with a conventionally used Mo/B(4)C multilayer.

Characterization of amorphous carbon films as total-reflection mirrors for XUV free-electron lasers

As part of the TESLA (TeV-Energy Superconducting Linear Accelerator) project a free electron laser (FEL) in the XUV (Extreme Ultra-Violet, (6-200 eV)) and X-ray (0.5-15 keV) range is being developed at DESY (Deutsches Elektronen Synchrotron, Hamburg). At the TESLA Test Facility (TTF) a prototype FEL has recently demonstrated maximum light amplification in the range of 80 nm to 120 nm. It is expected that the FEL will provide intense, sub-picosecond radiation pulses with photon energies up to 200 eV in the next development stage. In a joint project between DESY and GKSS, thin film optical elements with very high radiation stability, as required for FEL applications, are currently being developed. Sputter-deposited amorphous carbon coatings have been prepared for use as total reflection X-ray mirrors. The optical characterization of the mirrors has been carried out using the soft X-ray reflectometer at HASYLAB (Hamburger Synchrotronstrahlungslabor) beamline G1. The reflectivity of the carbon films at 2 deg incidence angle is close to the theoretical reflectivity of 95.6 %, demonstrating the high quality of the coatings. For comparison, layers produced by different methods (e.g. Chemical vapor deposition, Pulsed laser deposition) have been characterized as well. Annealing experiments have been performed to evaluate the thermal stability of the amorphous carbon films. Further investigations concerning the radiation stability of the X-ray mirrors have also been conducted. The mirrors were irradiated in the FELIS (Free Electron Laser-Interaction with Solids) experiment at the TTF-FEL. Microscopic investigations demonstrate that the carbon mirrors are fairly stable.

Recent developments of multilayer mirror optics for laboratory x-ray instrumentation

In this paper we review various improvements that we made in the development of multilayer mirror optics for home-lab x-ray analytical equipment in recent years. For the detection of light elements using x-ray fluorescence spectrometry, we developed a number of new multilayers with improved detection limits. In detail, we found that La/B4C multilayers improve the detection limit of boron by 29 % compared to the previous Mo/B4C multilayers. For the detection of carbon, TiO2/C multilayers improve the detection limit also by 29 % compared to the V/C multilayers previously used. For the detection of aluminum, WSi2/Si or Ta/Si multilayers can lead to detection limit improvements over the current W/Si multilayers of up to 60 % for samples on silicon wafers. For the use as beam-conditioning elements in x-ray diffractometry, curved optics coated with laterally d-spacing graded multilayers give rise to major improvements concerning usable x-ray intensity and beam quality. Recent developments lead to a high quality of these multilayer optics concerning beam intensity, divergence, beam uniformity and spectral purity. For example, x-ray reflectometry instruments equipped with such multilayer optics have dynamic ranges previously only available at synchrotron sources. Two-dimensional focusing multilayer optics are shown to become essential optical elements in protein crystallography and structural proteomics.

GISAXS with nanoparticles on liquids and with multilayer films on a lab source

The Microfocus Source IμS is a versatile device providing a very high X-ray flux within a small spot size. With this lab-source we have collected (GI)SAXS data of outstanding quality on liquid and thin-film samples with structures in the nanometer scale. In conclusion the IμS now enables (GI)SAXS measurements in the home-lab with a quality which was in the past only reachable at Synchrotrons. With the new IμSHigh Brilliance the flux could be increased by 30% for Cu, 50% for Ag and 60% for Mo radiation.

Current Status of Microfocus X-ray Sources for Chemical and Biological Crystallography

Modern microfocus X-ray sources define the state-of-the-art for most applications in X-ray diffraction. These sources are usually combined with multilayer X-ray mirrors which are excellent X-ray optical devices for beam shaping and preserving the brightness of the source. Microfocus rotating anode generators and liquid metal jet systems deliver flux densities in the range of 1011 photons/s/mm2. However, these sources are expensive and need regular and sometimes time-consuming maintenance. Low power microfocus sealed tube sources, such as the Incoatec Microfocus source IμS, represent an interesting low-maintenance alternative to rotating anode generators. Power loads of several kW/mm2 in anode spot sizes of < 50 μm deliver a small and bright beam. Flux densities of up to 1010 photons/s/mm2 can be achieved in a focused beam suitable for most protein crystals and poorly diffracting small molecule samples. The latest generation of the IμS, the IμS 3.0, is the first microfocus X-ray source that is optimized for X-ray diffraction resulting in a gain in intensity of about 30% compared to its predecessor. In this presentation, we will be reviewing the current performance levels of different microfocus X-ray sources. Further, we will be discussing the main features of the newest generation of the IμS. We will be presenting selected results to demonstrate the impact of these modern microfocus X-ray sources on the data quality for applications in chemical and biological crystallography.

Upgrading Existing Diffractometers with State-of-the-art Microfocus Sources

Modern microfocus X-ray sources define the state-of-the-art for a broad spectrum of applications in home laboratories, such as protein and small molecule crystallography, and small-angle scattering. These sources are combined with multilayer optics to image the source spot onto the sample. The optics provides a parallel or focused monochromatic X-ray beam, magnified to a suitable size. Low power sealed microfocus sources, such as Incoatec’s IμS represent an attractive alternative to rotating anodes, with a significant reduction in cost and maintenance. Power loads of a few kW/mm2 in anode spot sizes below 50μm deliver a compact brilliant beam. For example, the IμSHighBrilliance delivers up to 1010 photons/s/mm2 in a spot size in the 100μm range. It is available for Cu, Mo, Ag, Cr and Co anodes. Since the launch in 2006 more than 400 IμS are now in operation worldwide for a large variety of applications in biology, chemistry, physics and material science. Are you tired of getting spare parts for an ancient rotating anode or is your detector performance only limited by your beam delivery system? We will demonstrate how to bring former high end diffractometers back to a superb performance for cutting edge science after an upgrade with an IμS source. Incoatec ensures full software and safety integration, and an installation hand in hand with the local service, providing a constant service support from your partners on site. In addition to all Bruker or Nonius systems, Incoatec also offers integrations into a wide range of instruments from Rigaku, Marresearch or STOE, also with Dectris or Huber components.

Beam conditioning in cutting-edge X-ray analytical equipment

Nowadays, X-ray optical components, such as multilayer mirrors or scatterless apertures, are used as beam conditioning devices in nearly all state-of-the-art X-ray analytical equipment. Scatterless apertures, such as scatterfree pinholes, are usually made of oriented single crystals, and enable a beam conditioning that is free of parasitic scattering commonly associated with conventional metal apertures.[1,2] Therefore, such pinholes allow a significant improvement of small angle scattering instruments as the number of necessary pinholes can be reduced while simultaneously enlarging the beam defining pinhole size. This leads to an increased flux on the sample. Further, the use of scatterfree pinholes enables a significant reduction of the background. This improves the data quality at low resolution which is beneficial for small angle scattering, as well as for protein crystallography. Multilayer X-ray mirrors are widely used as monochromators and beam shaping devices in protein and small molecule crystallography, as well as in powder diffraction and small angle scattering.[3] Beam shaping with multilayer mirrors includes the optimization of the flux on the sample and the control over the beam shape and divergence. The mirrors comprise multilayer coatings that are deposited with a precision within ± 1% of the d spacing by physical vapor deposition techniques.[4] Very low shape errors below 100 nm and figure errors below 2 arcsec are required to ensure a superb flux density of more than 4 x 1011 phts/s/mm2 when combining multilayer mirrors with high-brightness microfocus X-ray sources, such as the novel liquid metal jet X-ray source.[5, 6] In this contribution, we will give an overview of current developments in multilayer optics and scatterless beam components, and show their benefit in combination with high-brightness microfocus X-ray sources for typical applications in small angle scattering and single crystal diffraction.

High-brilliance home-lab X-ray sources: status and future

Introduction Modern microfocus X-ray sources define the state-of-the-art for a number of applications such as protein crystallography and smallangle scattering in the home lab. These sources have anode spot sizes of 100 μm or smaller. They are usually combined with Montel multilayer optics as beam-shaping devices that image the source spot onto the position of the sample, magnifiying the beam to a suitable size. Multilayer optics deliver a parallel or focused monochromatic beam. Below results of three different microfocus sources are shown: a sealed tube source, a rotating anode source, and a liquid metal jet X-ray source. The power densities of these three X-ray sources range from several kW/mm2 for the sealed tube source, to about 20 kW/mm2 for the rotating anode source, and to more than 500 kW/mm2 for the liquid metal jet X-ray source.

New microfocus source for x-ray diffractometry in the home-lab

The increasing importance of X-ray diffractometry with one- and two-dimensional detectors for materials research has lead to a rising demand for highly intense X-ray sources enabling the analysis of very small and weakly scattering samples in the home-lab within a reasonable time frame. As a result, various microfocusing sealed tube X-ray sources with focal spot sizes below 50μm are now available. Potential applications of the low-maintenance, high-brilliance microfocus source IμS, which are equipped with different two-dimensional beam shaping multilayer optics, will be shown. With the instrumentation that is now available, more and more crucial measurements like gracing incidence small angle X-ray scattering or stress and pole figure measurements can be carried out in the lab, and even in-situ during dynamic processes. Some ideas on new instrumental set-ups for customized X-ray analytics will also be shown.

Total reflection and multilayer optics for synchrotrons and free-electron lasers

X-ray focusing technique is essential for probing microscopic samples at high pressures. Compound refractive lens (CRL) is one of the most versatile devices that are capable of focusing and collimating x-rays in the high-energy range of 20-60 keV [1, 2]. The CRL offers many advantages: good efficiency for focusing, compactness, robustness, and easy alignment (in-line focusing element). At high-pressure x-ray diffraction beamline BL10XU of SPring-8, the x-ray focusing optics consisting two different types of CRL devices have been installed in tandem. The first CRL (16 m focal distance) made from glassy carbon (GC), which is situated at a distance of 42 m from the source, has been used incidentally to collimate the x-ray beam. The aperture of this CRL is about 1 mm, whose size matches the beam size of the undulator. Because of difficulty in focusing the x-ray beam size down to 10μm through the first CRL, a second focusing CRL device was placed at 0.5 m upstream to the sample. The second CRL is sets of planar crosslenses with a quasi-parabolic profile for focusing in two directions, and were fabricated from SU-8 polymer by deep x-ray lithography at the ANKA in Germany [3]. The placement of the SU-8 CRL after the GC-CRL produces an x-ray beam with a spot size of less than 7 μm at 30 keV. The photon flux density at the focal point is approximately 10 photons/sec/mm. This x-ray optics allow us to collect highquality x-ray diffraction data on materials subjected to extreme pressures of up to 400 GPa, which exceeds the condition found at the Earth’s center. [1] A. Snigirev, et al., Nature 384 (1996),49-51. [2] Y. Ohishi, et al. , Nucl. Instrum. Methods A 467-468, (2001)962-965. [3] V. Nazmov, et al., Proc. SPIE 5539 (2004)235-243.