Single Crystal X-ray Diffractometer

Technical Specifications

X-ray Generator, anodes and monochromator

Spellman DF60N3 X-ray generator

The Spellman DF60N3 X-ray generator is the power supply of choice for all the Oxford Diffraction X-ray sources and is highly stable and reliable.

Two are housed within the Gemini base support and are controlled automatically from the CrysAlis software.
During a wavelength changeover, the control software directs one generator to de-energise as the other generator goes through its start up procedure to the selected power setting.

Electrical System

Technical data

Enhance (Mo) and Enhance Ultra (Cu) X-ray sources

 Enhance X-ray source (Mo)

The Enhance X-ray source is a complete optical assembly that generates a uniform and stable monochromatic X-ray beam at Mo-Kα wavelength.  The Enhance source typically generates 2.5 times more flux on the sample than a standard sealed tube with conventional optics.

Technical data

Enhance Ultra X-ray Source (Cu)

The Enhance Ultra X-ray source is a complete optical assembly that generates a uniform and monochromatic x-ray beam at Cu-Ka wavelengths suitable for single crystal diffraction of biological macromolecules. Based on inherently reliable and stable “Sealed Tube” technology, this source does not suffer the disadvantages of maintenance-intensive Rotating Anode systems.

Technical data

Monochromation

Enhance
Between the Sealed tube and fast shutter resides a channel cut [ACSF00050 (10x10x2mm) grade ZYA, flat 0,4°+/-0,1°thickness tolerance +0/-1mm] Highly Ordered Pyrytthic Graphite monochromator, that has been factory pre-aligned within the housing. Though often not necessay after a sealed tube exchange, there are two orthogonally mounted adjustments screws to aid beam optimisation in the unlikely event it is necessary
Enhance Ultra
The Confocal Max-FluxTM optics provide the best monochromatisation characteristics in the laboratory environment. This is an intrinsic property of multilayer Bragg-Reflection, with Peak reflectivity above 80% and FWHM approximately 400ev or 5%.

Automatic System for alignment of the X ray beam

The Gemini range of diffractometers have been designed to accurately change wavelength between Ka Copper and Ka Molybdenum at the touch of a computer screen button. After selecting a new wavelength, the currently used generator will de-energise at a pre-set rate to protect the longevity of the sealed x-ray tube and wait until a safe low temperature has been. Then the cooling water supply will divert to the newly elected x-ray tube. At the same time, the 0 degrees for the detector theta angle will realign onto the new x-ray source, and the CCD detector will load new software and firmware values relevant to the new wavelength. The new x-ray tube will automatically energise to a pre-set low level, and wait for voltage and current instructions from the user.

This automatic procedure takes less than 3 minutes in total, and ensures safe and reproducible wavelength changes that would NOT be possible using the old, physical exchange tube method and manual monochromator adjustment (~ 3 hours of careful manipulation)

Area Detector. Onyx CCD Detector

The Onyx CCD detector is a large area, fast readout CCD detector optimised for low noise and high sensitivity, and is ideal for measuring diffraction images from large unit-cell single crystals of weakly scattering materials and quasicrystals or disordered crystals.

Electrical system

Technical data

Goniometer. 4-circle kappa diffractometer

The 4-circle kappa diffractometer has been especially designed for Gemini so as to allow the co-mounting of the pre-aligned Twin Enhance X-ray sources, without reducing the class leading high angular resolutions – 0.37Å for molybdenum and 0.78Å for copper.

Electrical System

Technical data

X ray Protection cabinet

Regarding the protection cabinet - It is a light weight anodized aluminium frame with door and side panels glazed with a polymeric lead impregnated material which is the equivalent of 0.3mm of lead.  The recognized international standard is 0.25mm. All doors and side panels are fitted with invisible interlocks that render the system safe when open.

Video microscope

The video microscope records colour images, magnified 120 times, of the crystal mounted on the Gemini goniometer platform to assist with alignment, monitoring, and self-absorption corrections. The images are also transferred, stored and measured on the control computer.

Electrical system

Illumination of the crystal sample

The fibre-optic lighting system provides a bright and adjustable illumination of the crystal sample to improve the video imaging. The system is designed to deliver “cold light” and not transmit any heat energy to the sample area

Electrical system

CrysAlis Software package

The CrysAlis Software package is a comprehensive set of data acquisition and data reduction programmes for single crystal diffraction experiments performed on any of Oxford Diffraction’s Xcalibur or Gemini diffractometer systems. CrysAlis is supplied on a multi-user, multi-site licence basis, thereby far exceeding the 4 license requirement of the Public Contest No 1/2006 of the IBMC. Upgrades are available to users approximately half yearly and equally free of charge. Please note that, at the time of writing, a brand new Software package called CrysAlis Pro is being prepared for release in December 2005. This has many more features and will be described in future communications.

Low temperature sample environment

All sample environment devices used by Oxford Diffraction are easily interchangeable due to the universal mounting on the Gemini platform service tower.

Cryojet XL

Oxford Instrument’s Cryojet XL nitrogen jet has been designed specifically for the cooling of monocrystal samples for x-ray diffraction experiments. The nitrogen flow circuit could not be simpler. There are no mechanical pumps or line desiccators, just a vacuum insulated flexible line from the storage dewar to cryostat head. There are no moisture traps requiring regeneration – in fact, there are no moving parts at all. These features mean that the system has minimal maintenance requirements.

Electrical system

Technical data

Autofill

Oxford Instrument’s Autofill facility extends the useful operating time of the Cryojet XL such that re-fills become a weekly scheduled activity. The nitrogen level meter attached to the Cryojet XL will register a low level in the 75litre dewar and automatically order a refill from the attached 160litre self pressurised dewar. Once full, the filling will stop automatically. As with Cryojet XL itself, there are no mechanical pumps or line desiccators, just a flexible line from the wheeled, self-pressurised dewar to the Cryojet XL storage dewar. This facility can be monitored and controlled through the CrysAlis S/W (ODBench).

Electrical system

Technical data

Cooling Systems

CCD Cooler unit, KMW200CCD

The KMW200CCD is a closed cycle cooler unit to provide cooling to the Peltier circuits in the CCD detector head.

Electrical system

Technical data

X-ray tube cooler unit, KMW3000C

The KMW3000C cooler provides stable cooling of the X-ray tubes used on the Gemini diffractometer. During a wavelength changeover, the control software automatically redirects the cooling water supply to the energising tube after the de-energised tube has reached a safe temperature.

Electrical system

Technical data

UPS (Uninterruptable Power Supply)

The APC Smart-UPS RT 7500VA RM UPS sets the standard in its industry for quality, innovation and support. Its comprehensive solutions, which are designed for both home and corporate environments, improve the manageability, availability and performance of sensitive electronic, network, communications and industrial equipment of all sizes. The mission of APC is to improve the manageability, availability, and performance of information and communication systems through rapid development and delivery of innovative solutions to real customer problems.
Electrical system

Technical data