STOE LINEAR PSD AND DECTRIS MYTHEN 1K DETECTOR
Transmission and Bragg-Brentano measurements showing a significant increase in intensity for the data collected with the MYTHEN 1K silicon strip detector in comparison to the STOE linear PSD.

STOE has developed a new type of diffractometer which is more flexible than any existing system without any loss in performance. The STADI MP combines the two most common diffractometer configurations: Transmission/Debye-Scherrer and Bragg-Brentano geometry with a set-up for micro-diffraction.

The very reliable, high-precision two circle goniometer is the basis of a whole range of x-ray powder diffraction solutions. Vertically or horizontally mounted, the STADI P can be built-up in Transmission/Debye-Scherrer or Bragg-Brentano geometry: Transmission/Debye-Scherrer, Reflection/ Bragg-Brentano or both. Two STADI P goniometers, either in the same or different configurations, can be mounted in the same cabinet resulting in two completely independent units. Moreover, two goniometers can share one source.
WHY MEASURE POWDER IN TRANSMISSION- / DEBYE-SCHERRER GEOMETRY?

Based on the well known STADI P, STOE has developed a new powder diffractometer for high-throughput and combinatorial measurements in transmission geometry. With its newly designed sample stage providing a variable x,y grid for various slide-in sample holders, eg. for up to 96 different samples, the STADI P COMBI offers highest efficiency combined with all the advantages of the STADI P system.

The STOE Powder Diffraction Software Package WinXPOW is a state-of-the-art 32-bit Windows application.
Transmission and Bragg-Brentano measurements showing a significant increase in intensity for the data collected with the MYTHEN 1K silicon strip detector in comparison to the STOE linear PSD.
Although scintillation counters are still widely used there are more sophisticated types of point detectors with higher quantum efficiency and the possibility to directly discriminate the energy of the incident radiation. Therefore samples of Li2SrSiO4, K3[Fe(CN)6], Fe and Mn2CrO4 were investigated using a STOE STADI MP with pure Cu Kα1 radiation.
The data measured with a scintillation counter (with and without a secondary beam monochromator) were compared with data from a Si PIN diode point detector. The latter allows to cutting off the fluorescence of Fe/Mn completely, which results in data outclassing a scintillation counter with secondary beam monochromator in absolute intensity and resolution.
The Si PIN diode point detector is superior to a scintillation counter without secondary beam monochromator in terms of the signal-to-noise ratio as well as the FWHM of the reflections due to the better quantum efficiency and lower height divergence.
Request labnote:
A STOE STADI P powder diffractometer with Ge(111) monochromator yielding pure Ka1-radiation and the Dectris MYTHEN 1K detector has been chosen for PDF calculation experiments on Naphtalen (C10H8). For Cu K(alpha)1-radiation the Stoe Stadi P has been equipped with a Dectris MYTHEN 1K with 320 μm, for Mo K(alpha)1-radiation with a MYTHEN 1K with 450 μm and for Ag K(aplha)1-radiation with a MYTHEN 1K with 1mm chip size. Synchrotron data has been taken at beamline X17A at NSLS Brookhaven (λ=0.1839Å).
The MYTHEN 1K detector from DECTRIS has been implemented on STOE’s STADI P and MP diffractometer and used as the ultimate PSD for fast measurements with ultra high resolution. With a NIST SRM660a LaB6 standard powder sample, an angular resolution below 0.03° 2(Theta) FWHM can be achieved.
In the optimized setup, the detector simultaneously collects an angular range of 12.5° 2(Theta) with native data point intervals of 0.01° 2(Theta). In the expert mode, patterns with data point intervals up to 0.005° 2(Theta) can be measured. Due to its wide detector window, the MYTHEN 1K detector collects very fast, additionally keeping the outstanding angular resolution constant over the complete opening.
To observe the influence of the wavelength and the detector noise using a laboratory powder diffractometer for the PDF determination and the maximum evaluable Q-value a 1mm glass capillary has been filled with Pigment Yellow 213 (PY213) and adjusted on a goniometer head of a STOE STADI P powder diffractometer in Debye-Scherrer geometry at the STOE application lab.
Low temperature measurement of TbVO4 with a closed cycle helium cryostat and a STADI P.
STOE provides the ideal equipment for powder diffractometer systems to observe and evaluate transitions in nonambient environments. With the ultrafast MYTHEN 1K Stripdetector manufactured by DECTRIS very rapid measurements can be perfomed. Highest quality data is obtained with the STOE capillary furnaces for powder investigations at high temperatures. The STOE furnaces can be mounted on every STADI P or MP diffractometer (moving circles or fixed stage).
Two measurements using the same settings had been accomplished, one with the sample material and the other with an empty sample holder. The latter had been subtracted from the first, to eliminate effects of the primary beam. It is admirable to see that small angle measurements down to 0.2° 2q (using Cu K(alpha)1-radiation) or appr. d-values of 440 Å can be executed with a STOE STADI P without any further equipment like i.e. a Kratky collimator etc.
The DECTRIS MYTHEN 1K strip detector has been implemented to the STOE powder diffractometer and
software. The examples show to some extent the possibilities of this combination of outstanding equipment for powder diffraction experiments. Extreme fast measurements of typical powder samples are now possible due to the high sensitivity of the MYTHEN 1K detector. A full pattern from 0° to 120° 2q can be recorded in 60 seconds with a still good signal to noise ratio as shown in the labnote.
Though still less common in the crystallographers’ community, the Transmission geometry is the method of hoice for the investigation of powder samples. Using a Stoe Stadi P powder diffractometer the focusing Ge(111) monochromator yields pure K(alpha)1-radiation for the highest resolution in 2(Theta) (FWHM < 0.03° !). Furthermore the Transmission geometry provides reliable intensities over the full 2(Theta) scale.
Transmission geometry data never suffers from height displacement, samples measured in a capillary are nearly unaffected by the distracting effects of preferred orientation. Even the smallest amount of samples can be evaluated when prepared between two foils. Besides this micro sampling Transmission geometry enables diffraction measurements at the lowest 2q angles.
Measurement of LaB in a 0.3mm capillary on a STOE STADI P powder diffractometer with Ag-Kα1 radiation in Debye-Scherrer mode up to 90° 2Theta (d=2.75A!).
The properties of thin films affect their reflection and interference characteristics. The two most common ways to measure these are reflectometry and ellipsometry. The STOE thin film attachment uses the total scattering method and detects the reflected amount of X-ray radiation from a thin film. It allows analyzing the thickness of layers in the nanometre scale. For example, single-layer or multilayer films of semiconductor process films can be analyzed.
With the possibility to be set-up vertically as well as horizontally, the STADIVARI increases its scope of application.
The STADIVARI can be used for single crystal and powder diffraction. The Open Eulerian Cradle offers enough space to add high pressure cells, high- or low- temperature devices or other chambers.
In the dual beam setup, all combinations of tubes and microfocus BDS are possible: two sealed tubes, one sealed tube and one microfocus BDS or two microfocus BDS.
As the youngest member of the long line of STOE diffractometers, the STADIVARI is fully integrated in the well-established STOE X-Area software package.

STOE’s IPDS 2T combines all the achievements of the IPDS II with the possibility to turn the whole goniometer around the Θ axis to an angle of up to 60° yielding a 2Θmax of 137°! This additional axis makes the IPDS 2T a diffractometer of unique versatility. Featuring also the dual beam capability for using two different wavelengths on the same instrument the structure solution of small molecules and proteins as well as electron density determination and powder investigations are no challenge for the IPDS 2T.

Unparalleled reliability, built to serve all scientific needs: e.g. small molecules, proteins, electron density measurements. Full accessibility of the sample environment for easy adaptation of high and low temperature attachements as well as high pressure cells.

The new 32-bit software X-Area has been designed to work on all STOE Imaging Plate Detector Systems, the IPDS II, the IPDS 2T and the new STADIVARI equipped with the DECTRIS PILATUS detector. It includes the well known software tools:
Powder and single crystal data with different exposure times have been collected to prove the excellent performance and noise behavior of the Pilatus detector.
Although Mo Kα radiation is widely used in routine small molecule structure determination, a number of applications in chemical crystallography are best treated with Cu Kα radiation. These include studies on weakly diffracting and/or very small crystals, measurements on partially disordered or fibrous samples, absolute structure determination and others. To evaluate the suitability of the STOE image-plate system IPDS2T equipped with a GeniX Cu Kα microbeam system manufactured by XENOCS for applications in chemical crystallography, trial measurements on two samples that are commonly used for testing purposes have been performed.
Chemical crystallography applications with the STOE IPDS 2T diffractometer equipped with a Xenocs GeniX Cu Kα microbeam system.
Solving protein crystal structures by single-wavelength anomalous diffraction (SAD) from sulphur atoms has become a widely advocated technique in recent years. This method has several appealing features, on the other hand, given that the anomalous scattering strength from sulphur atoms is rather weak at these wavelengths (f”=0.557 at Cu Kα), the data have to be collected with a very high degree of accuracy, completeness and redundancy. Such measurements are therefore ideal to test the capabilities and performances of a laboratory diffractometer setup.
The STOE IPDS 2T has proven as a powerful instrument in the collection of high resolution and high quality data for electron density determination.
On an STOE IPDS II and IPDS 2T resp. powder samples can be examined as well as single crystals. Additional accessories are not required. Textures and grain size effects can be recognized easily. Diagrams ‘intensity as a function of 2Θ’ can be created from the frames with the aid of a STOE tool.
The powder samples to be examined are filled into glass or quartz capillaries which usually have a diameter between 0.2 and 0.7 mm. During an exposure a capillary can be rotated automatically about one or two goniometer axes all the time to yield best-possible statistics. Debye-Scherrer rings (powder rings) are obtained as shown in the following example (0.5 mm capillary with silicon powder, IPDS II, 2 kW, Mo-Kα (point focus), planar graphite monochromator, 40 mm detector distance, 5 min irradiation).
STOE develops, manufactures and sells scientific instruments for the non-destructive analysis of substances. Based on the X-ray diffraction (XRD) method, these systems characterize single crystals and powder samples and give answers to which substances a particular powder or crystal contains or at which positions atoms in solid bodies are exactly located.
09.11.2020
Allgemein
With this newsletter, we are proud to launch innovations for STOE powder and single crystal XRDs: • - the fully new developed WINXPOW application working with ICCD PDF2/PDF4 and COD • - watch the DECTRIS product launch with first-hand exper...
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