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SAXS Ganesha


Location:  8B Shepherd Labs

Contacts: 

User Guideline Agreement

Radiation and Lab Safety

Instruction Manual   [  PDF 335kB]

Description:

Ganesha, at CharFac, is a customized, state-of-the-art small-angle X-ray scattering (SAXS) instrument. It incorporates many options for sample environments and has additional capability to measure in the grazing incidence. The specific attributes of the instrument are full motorization, extensive automation, and a control interface that caters to all levels of expertise. Some of the important features are

  • X-ray Microsource with Cu target and Integrated Monochromator (2D graded index multilayer optimized for SAXS).
  • Beam collimation with three motorized 4-blade "scatterless" slits from single crystal Si with atomically smooth edges (allowing for a factor of 1000 in the q-range from 3.5E-3 to 3 Å-1).
  • Automated to run in 2-pinhole (high flux) or 3-pinhole (high resolution) configurations.
  • The beam path - evacuated by oil-free high speed pump allowing full pump-down to operating pressures in 4 minutes.
  • The sample stage - fitted with XY chi-theta goniometer for alignment and position samples for transmission and grazing incidence work. A large heavy duty YZ-stage placed below goniometer.
  • Detector- Position sensitive Eiger 1M (Dectris), uses the latest Hybrid Photon Counting (HPC) technology. The detector offers outstanding data quality through (i) no readout noise or dark current - highly improved signal-to-noise ratio, (ii) small pixels and excellent point-spread function - high spatial resolution (iii) continuous readout and global shutter - high duty cycles.
  • Eiger Detector mounted on an automated trail, sample to detector distance can be varied from 10 to 150 cm and data captured in the q-range 0.003 to 2.7 (d-spacing 2.3 to 2000 Å).
  • Pilatus 100 k detector for simultaneous WAXS, which can be moved to cover 2θ range from ~27 to 85°

Sample and environment options:

Large and versatile sample area that allows for the introduction of a wide range of sample environments within the existing chamber.

  • Versatile sample holder. For powders, non-viscous liquids in capillaries, stand-alone polymer sheets/films/tubes. Possible to load upto 60 samples simultaneously.
  • Sandwich sample holder. For viscous gels sandwiched between kaptone/mica sheets and contained within stainless steel holders.
  • Multi-capillary stage (JPS). Variable temperature SAXS for liquid samples contained in capillaries (6 capillary sample stage; temperature range -2? to 80 °C). Ideal for aqueous systems of low to moderate viscosity. This stage can enable quantitative background subtraction due to the ability to expose the same region of the same capillary.
  • Linkam heating stage. Variable temperature SAXS for viscous gels contained in sandwich cells. (Temperature range -150 to 300 °C and heating/ cooling rate: 0.01 to 30 °C/min). Accommodates one sandwich cell.
  • Four-position heating stage (INSTEC). Variable temperature SAXS for viscous gels contained in sandwich cells. Accommodates four sandwich cells. Temperature range from -30 to 80 °C.
  • Linkam shear cell (CSS 450). Vertical Shearing of viscous fluids for X-ray probing transverse to shearing direction. Temperature range- ambient to 450 ºC (rates of 0.01 to 30 ºC/min). With sample area 30 mm and gap setting between 5 and 2500 µm, microstep motor allows 25,000 steps per rev.
  • Linkam tensile stage. Designed to apply uniaxial strain on the sample while collecting SAXS data. The stage is available in two versions, with a force transducer of 0-20 N with a resolution of 0.001 N, or one of 0-200 N with a resolution of 0.01 N. Temperature range -150 to 250 °C, heating/cooling rate 0.01 to 30 °C/min.
  • Grazing incidence. Used to characterize surface structures of the sample. Depending on scattering geometry, either vertical (scattering is horizontal) or horizontal (scattering is vertical) sample holder may be used.
  • Atmospheric pressure instrument configuration. Some stages (such as Linkam Shear Cell) and sample types are incompatible with high vacuum and thus require isolation of the sample environment from the vacuum chamber. The ambient pressure instrument configuration isolates the sample environment from the high vacuum required to minimize air scattering and to protect the detector. This configuration greatly expands the capabilities of the instrument, though the lack of vacuum increases background air scattering, reducing the resolution of the instrument.