NOT AVAILABLE

STATION 9.5HPT
High Pressure Powder Diffraction Crystallography

Description

Diamond anvil cell high pressure sample environments. Powder diffraction from these cells recorded using image plates

Functional Description

Station 9.5 provides a focussed monochromatic X-ray beam of ~0.5 Å for high pressure studies using diamond anvil cells.

Technical Description

White beam X-radiation is taken into the station. A silicon crystal cleaved parallel to the 110 plane is used in Laue geometry to produce monochromatic beams, of which the 111 reflection is selected as the X-ray beam for experiments. The diffracted beam is displaced horizontally from the direction of the incident beam.

Bending the crystal allows focusing of the monochromatic beam over a distance of four metres, intensifying the radiation. This focused beam is used to probe samples contained in diamond anvil cells. Diffraction from crystalline phases within these cells is then recorded on image plates for subsequent processing.

Two methods of data collection are available. A Molecular Dynamics 'Storm' scanner is used to produce .gel files from the image plates. Alternatively, on-line data collection is now available using a mar345 image plate detector. Software for integration of powder diffraction data collected using either of these two methods is available on the station computers. See the SRS homepage for a short article on the installation and testing of the mar345 detector.

Development

The Laue focussing system has proved effective for producing high intensity X-rays. The station has been fully converted for high pressure studies, with a modular arrangement of adjustable benches and optical rails being installed to allow rapid changes in experimental configuration to be made.

Proposed Development

Further developments to aid rapid data collection will be implemented shortly. These will include in-line pressure measurement and automation of diamond anvil cell pressure change.