- Chemical Crystallography
- IµS-Mo for ChemCryst
- IµS-Ag for ChemCryst
- METALJET for ChemCryst
The precise determination of the three-dimensional crystal structure of a compound is crucial to understanding the properties and function of the material. This is a key task in drug design and materials research where compounds of both chemical and biological interest are studied - for example new synthetic chemicals, catalysts, pharmaceuticals, natural products, proteins, and minerals. Generally, single crystal X-ray diffraction (SC-XRD) is the method of choice for obtaining very accurate three-dimensional structural models.
Since its introduction in 2004, the Incoatec Microfocus Source has become the gold standard for high-brightness microfocus sealed tube sources in chemical crystallography. Compared to Cu-Kα, shorter wavelength radiation, such as Mo-Kα or Ag-Kα, allows diffraction experiments with minimized absorption and higher crystallographic resolution. Therefore, Mo-Kα is the favored wavelength for home-laboratory crystallography on small molecules and inorganic compounds, while Ag-Kα radiation is favorable for diffraction experiments on strongly absorbing materials and for high pressure crystallography.
The Incoatec microfocus source IμS in combination with a Bruker Smart Apex II
The Incoatec microfocus source IμS in combination with a Nonius Kappa CCD diffractometer
Charge density study on oxalic acid
IµS-Mo for Small Molecule Crystallography
Diffraction experiments for routine structure determination show that the 30W IµS Classic for Mo-Kα radiation clearly outperforms standard Mo fine-focus sealed tube X-ray sources that were typically used in small molecule crystallography. It delivers 1.5 times the flux density of a 5 kW rotating anode plus graphite monochromator, at only 30 W. As he FWHM of the beam from IµS is about 110 µm, the IµS is the X-ray source of choice for small and challenging crystals. The IµS gives a three-fold intensity gain for very small crystals (edge length ≤ 0.1 mm). For medium sized crystals (edge length 0.1 - 0.2 mm), the integrated intensity is comparable to that of a rotating anode generator with a graphite monochromator. Furthermore, the latest version of the IµS, the IµSHigh Brillance, delivers 60% more intensity than the IµS Classic, thereby, clearly outperforming 5 kW rotating anodes. Therefore, the Mo IµS HB represents a very attractive low-maintenance and energy-saving alternative to rotating anode systems.
The Ag-IμS on a Bruker AXS APEX II QUAZAR goniometer with a Be-free DAC and modified collimator
IµS-Ag for Material Science
The IµS for Ag radiation is the microfocus sealed tube X-ray source for single crystal and powder diffraction using short wavelength radiation. It either delivers a focused beam with a FWHM of 95 µm and a divergence of 5 mrad suitable for diffraction on single crystals, or a beam with a FWHM of about 155 µm and a divergence of 2.5 mrad suitable for diffraction experiments on smaller amounts of powder samples (e.g. in a diamond anvil cell).
The advantages of Ag radiation are the reduced absorption and extinction, and the „compression" of the reciprocal space. Thus, data are less biased by absorption and extinction, and access to a larger range of d-spacings at a fixed 2θ setting is gained. This is beneficial for high resolution diffraction experiments, such as studies on strongly absorbing inorganic solid state compounds or charge density measurements, and for high-pressure crystallography on single crystals and powder samples.
The METALJET X-ray source in a D8 VENTURE
Calculated precession pattern of the 0kl layer and deformation density for Cytidine
Small Molecule Crystallography with METALJET
The METALJET X-ray source for small molecule crystallography uses either focusing HELIOS MX Ga or focusing HELIOS In optics that contain synchrotron-class quality multilayer mirrors delivering the smallest and most intensive X-ray beam of any home lab X-ray source.
Due to the shorter wavelength of the Ga-Kα radiation compared to Cu-Kα radiation, the highest resolution achievable with the METALJET X-ray source is typically about 0.70 Å, compared to about 0.80 Å for Cu-Kα. Hence, about 50% more unique reflections can be recorded. These additional reflections significantly improve the quality of the structure model.
The resolution and the number of accessible unique reflections are even further improved by using the In-Kα line of an Indium containing alloy. With a wavelength of 0.51 Å, the highest achievable resolution of the liquid Indium METALJET is below 0.30 Å, giving a more than 2-fold gain in unique reflections compared to setups that use Mo-Kα radiation. This sub-atomic resolution can only be accomblished outside synchrotron beamlines with the METALJET X-ray source.