Fyzikální ústav Akademie věd ČR

Head: Michal Dušek

The main experimental tool for investigating atomic structure of monocrystals with x-ray diffraction is the four-circle diffractometer Gemini with CCD detector Atlas. This modern instrument installed at the beginning of 2008 ranges to the best machines of this category in terms of sensitivity and data collection speed. It allows for very exact measurement of satellite reflections of aperiodic crystals.

Gemini has two x-ray tubes, with copper and molybdenum anode, and it can switch automatically between them. The molybdenum tube provides x-rays of the vawelength 0.71073 Å collimated with fibre-optics collimator. The beam diameter can be set from 0.3 to 0.8 mm. This radiation can be used for studies of inorganic and organometallic materials including strongly absorbing samples. The copper tube provides x-rays of the wavelength 1.54184 Å collimated with thin-layers mirrors (collimator Cu Enhance Ultra) to a beam of the diameter 0.3 mm. The intensity of the focused beam is sufficient for measurement of organic samples, from small molecules to well diffracting proteins.

The laboratory of single-crystal x-ray diffracton provides measurements and calculations of crystal structures on the basis of scientific collaboration to a wide spectrum of users from Institute of physics, Czech Republic and from abroad. The throughput is around 400 samples per year.

Diffractometr Gemini. (1) Goniometric head with the sample; (2) Area CCD detector Atlas of x-rays; (3) Molybdenum x-ray tube and collimator of molybdenum radiation; (4) Copper x-ray tube and collimator of copper radiation; (5) Open-flow nitrogen cooler; (6) Goniometr for rotating the sample to the diffraction position

Mounting the sample on the diffractometer Gemini. (1) Goniometer head; (2) Glass hair with the sample glued on the top; (3) Collimator of copper radiation; (4) Collimator of molybdenum radiation; (5) Nozzle of the open-flow nitrogen cooling device; (6) Beamstop for x-ray primary beam; (7) Area detector Atlas.

Measured sample as seen in the videomicroscope. (1) The crystal of the measured samples, height 0.1 mm; (2) Top of the glass hair.

X-ray diffractions registered witj area detector. The shadow of the beamstop can be seen on the right against a higher background of the scattered beam.