mySpot Beamline

mySpot Beamline is used to provide stable beam especially tuned for the mySpot experiment. Depending on the experiment requirements, different optical devices are used. The schematic view shows two different configurations, one tuned for low divergency, and one for narrow energy band width, as required for the scattering and spectroscopy experiments respectively. Since the goal of the experiment is to provide several methods at the same time, beamline properties can be tuned to provide the optimal beam for a given combination of experiments. Total intensity, divergence, energy resolution, high harmonics suppression, and stability in scans can be tuned to match the requirements. For details, please visit the experiment page.

Schematic view of the beamline

3 monochromators of the mySpot Beamline, left to right: Si111, Si311, B4C/Mo Multilayer

Except 3 different monochromators, the beamline features the second, bimorph adaptive mirror, which is used to vertically focus the beam below 50µm. The mirror has 3 tracks, which are used for the suppression of higher harmonics.

Micro-XANES, -EXAFS, -fluorescence Station

Micro-XANES, -EXAFS, -fluorescence, -SAXS, -WAXS, -Raman Scattering

mySpot is a versatile microfocussing station for scanning methods with resolution down to 1.5 µm, providing a combination of methods which can be performed simultaneously at the same sample position. It is especially designed (but not limited to) for the study of hierarchically structured biological samples. Structural information from different scales (XRD - crystalline, SAXS - nanometer, Video-microscope -- micrometer, sample translation - milimeter) can be combined with chemical information (XRF-mapping, EXAFS, XANES) and molecular information (Raman) providing unique insight into the mutual dependencies of different parameters.

The beamline provides focal spot of about 500x50µm, which can be refocused at the sample using capillary optics. Capillary optics is used for two main reasons: 1) the focal spot does not depend on the energy which makes EXAFS and XANES measurements very simple, and 2) the optics is positioned very close to the sample which improves the stability of the focus at the sample.

This makes the focal spot of 1.5 µm in 2D scans possible, as well as very parallel beam for scattering experiments down to 10µm, or volume element of 20µm diameter for 3D XRF mapping.

Photon Flux depends on the monochromator and divergency. Image shows the flux for the Si111 and Multilayer monochromators.

Data acquisition schematic for the mapping experiment. All the detectors are simultaneously evaluated and the data can be imediately evaluated for the better planning of the next steps.

Piece of the Kumran parchment during 3D XRF scan.

Methods

The mySpot beamline is specialized for mapping experiments using different methods. Depending on the required method the focus varies between 1.5 and 100µm. Most methods can be combined. However, the user should take into account that the beam requirements vary for different methods. Example: For XRF mapping with 1.5 µm focus the beam is strongly focused to the sample, providing enough intensity to perform even EXAFS at selected positions. If small angle scattering from the same position is required, this strong focusing is not possible, rendering simultaneous microEXAFS and SAXS with 1.5µm focal spot very complicated.

Following methods are available and can be combined with restrictions:

1) micro-XRF mapping. Detectors available: 7 channel Si(Li) detector with 210mm² surface or 80mm2 Silicon drift detector. The smaller detector is used for combined scattering/XRF measurements. Resolution depends on the used optics and can be selected between 1.5 and 20µm. Primary beam energy range is 6keV-25keV.

2) 3D XRF-Mapping. 7 channel detector is used, althogh only one channel is assigned to the volume mapping. This allows for the acquisition of the fluorescence signal from different directions and estimation of the inelastic scattering. For this method we use polycapillaries with focal distance of about 3 mm and focal spot od about 15µm.

3) X-Ray scattering. SAXS and WAXS signal can be acquired using a Dectrix Eiger area detector (3000x3000 pixel, 50µm pixel size) positioned downstram from the sample. Maximal scattering angle is 45°, resolution in SAXS regime is 0.1 nm^-1 (0.01 Å^-1 - d-spacing up to ~ 60 nm).

4) micro-EXAFS and XANES. Capillary optics allows the acquisition of the energy-dependent absorption spectra on selected position at the sample. 

5) Visible/NIR Raman scattering. It is possible to acquire Raman spectra in combination with X-ray m3easurements. For this two different Raman systems are available. In-line Renishaw Raman spectrometer (in cooperation with MPIKG Golm) allows for very precise Raman spectra to be acquired, using laser axcitation parallel to the X-ray beam. For the combination with XRF measurements, a smaller, faster (down to 0.1s per spectrum) system can be mounted where the laser excitation is illuminating the sample at the 45° twith respect to the X-ray beam. Both systems provide wavelengths 532 and 785nm.

6) Optical microscope is available for alignment purposes, but the microscopy images can be saved at every measurement coordinate, so that the correlation between the measured data and the microscopy is rather simple.

Sample environments:

Different scanning environments for different sample sizes (from several micrometer to 150mm) are available at the beamline. Rotational units are available for both scattering and fluorescence methods.

There is no vacuum environment available at the beamline, but it is possible to mount sample environmets or reactors at the available 1-circle goniometer in the experimental hutch. Different experiments were successfully mounted at the station, including in-situ stretching devices, plasma chambers, laser-levitation sample holders...

Sample cooling for very small samples is available through cryo stram down to -150°C. For larger samples a Linkam cryo-scanning chamber is available, providing temperatures between Liquid Nitrogen and 200°C. Only clean, non-gasing samples are accepted for heating experiments.

Temperature and humidity in experimental hutch are controlled.

For information about complicated measurements please contact the beamline scientist.