STATION 9.8
High Flux Single Crystal Diffraction

Description

This station is a high flux, tuneable, monochromatic, single crystal diffraction station for structure determination in chemistry and materials science.

It utilises a Bruker-Nonius APEXII CCD area detector and diffractometer at X-ray wavelength between 1.45Å and 0.30Å. Variable temperature data collections ranging from 85 to 600K along with high pressure environment using a diamond anvil cell are available.

The station is currently used in the following ways

1. Structural studies on small and weakly diffracting materials
2. High resolution data collection for charge density studies
3. Anomalous dispersion experiments
4. High Pressure experiments

News

Removal of the APEXII diffractometer for repair back in Madison. (21/07/05)

9.8 reaches new limit on space collecting over 300 GB of data in one AP (and the AP isn't over yet!). (21/07/05)

Functional Description

Station 9.8 is a high flux single crystal facility which utilises a Bruker-Nonius APEXII CCD area detector and D8 diffractometer at X-ray wavelength between 1.45Å and 0.30Å. Variable temperature data collections ranging from 85 to 600K along with high pressure environment using a diamond anvil cell are available.

The station is currently used in the following ways:

1. Structural studies on small, and weakly diffracting materials
2. High resolution data collection for charge density studies
3. Anomalous dispersion experiments
4. High Pressure experiments
5. Single crystal environment experiments

Technical Description

At 10.7m from the 5T wiggler, the station can receive up to 3.8mrad of beam depending on the monochromator.

This is focussed in the horizontal plane by a cylindrically bent asymmetrically cut triangular Silicon monochromator, cooled by GaInSn alloy. There is a choice of either a 111 or 220 monochromator crystal. The 111 crystal has an asymmetric cut of 2.01°, which gives in an optimum focus at the sample for a wavelength of 0.7Å. At this wavelength the deltalambda/lambda = 0.1%. The operational range of this crystal is from 1.45Å to 0.45Å. The 220 crystal has an asymmetric cut of 1.03°, which gives in an optimum focus at the sample for a wavelength of 0.3Å. At this wavelength the deltalambda/lamdba = 0.1%. The operational range of this crystal is from 0.8Å to 0.30Å. The monochromator is mounted on a Huber rotatory table and can be positioned to a precision of 0.001°. For normal use the station is set to approximately 0.68Å.

The second optical component is a flat 1.2m palladium coated (300 mm) zerodur glass mirror. This is mounted to allow it to be cylindrically bent to provide vertical focussing of the monochromatic beam. Its second purpose is to act as a harmonic rejecter. At 0.68Å the mirror operates at 6mrad to the incident beam. The mirror has been successfully used between 0.48Å and 1.45Å.

The station operates a Bruker-Nonius APEXII CCD area detector and D8 diffractometer.

The APEXII has a choice of four standard collimators (0.8, 0.5, 0.3, 0.2 mm) plus two for microcrystal work (0.1, 0.05mm under test). The uncollimated beam is 2.5mm in width by 1.0mm high.

1. Oxford Cryosystems Cryostream 700+ series - temperature range from 85 to 500K
2. Hot gas stream - temperature range from 373 to 600K
3. Diamond anvil cell - for studies where the sample is maintained at high pressure
4. Crystal environmental cell for studying single crystal diffraction whilst exposing the crystal to vacuum or a gas environment

Development

With the installation of the new diffractometer in March 2004 we have also undergone a radical upgrade to all the data collection and processing. Whilst also upgrading the traditional integration software (SAINT) to allow the processing of twinned datasets.

2003/2004 has also seen a new and improved user area, including:

• Air conditioning
• New long working distance microscope (Nikon SMZ1000 with reticule)
• LCD Monitors
• New 2GHz data processing computer
• New furniture
• Remote control of Oxford Cryostream (700+ series)
• Micrometer added to allow ease of focus on diffractometer CCD camera
• microscope

Proposed Development

1. Further work is planned for the gas environment cell which will hopefully become a user facility in the near future
2. Reorganisation and rationalisation of station facilities and space
3. An offline processing area

In the longer term it is intended that both station 9.8 and 16.2 SMX are linked via a database and data storage server. This would allow easy access to user data, the ability to store greater quantities of user data for longer periods (at the moment we are producing so much data that we generally exceed our machine limits within two weeks) and the ability to work on datasets whether the user collected them on 9.8 or 16.2 SMX.

Typical Experiment Turnaround Time

A standard structural data collection (a full sphere with step width of 0.30° and a counting time of 1sec) takes around 1 hour and 30 minutes. A full sphere utilising 1.0° frame widths will take around 30 minutes.