Small-Angle X-ray Scattering (SAXS)

Small-Angle X-ray Scattering (SAXS)

This instrument is used to characterize materials in terms of internal dimensions that are roughly 50 to 500 times the size of a chemical bond (Ångstrom scale) by means of X-Ray scattering. This is the typical size range described as “Nanotechnol-ogy.” The instrument also has an image plate detector, which makes it possible to measure wide-angle X-ray diffraction (WAXS) at the same time as SAXS is meas-ured (“simultaneous SAXS/WAXS”).

SAXS is used for characterizing biological macromolecules such as proteins in solu-tion.  It is also used to characterize a range of other materials including: polymers, macro-porous materials, bone, graphene, etc.  

The instrument is equipped with:

  • Thermoelectric (“Peltier”) temperature controlled sample holder (-20 C to + 120 C).
  • Tilt stage and special beam-stop for grazing-incidence SAXS (GI-SAXS).
  • “Stretch” stage that allows a polymer sample, for example, to be stretched, in situ, along one axis, perpendicular to the beam.

Approximate measurement ranges for detectors using standard (“high flux”) pin-holes:

  Detector q-range (reciprocal Å) d-spacing (Å)
SAXS

Bruker HiStar
105 cm from sample (standard position)

0.014 to 0.2 30-440
SAXS

Bruker HiStar
65 cm from sample

0.02 to 0.34 18.5-300
WAXS Fuji Image Plate 0.2 to 5 1.25-30
Manufacturer: Bruker

Some instrument specifications

The x-ray source is a rotating anode with a copper target and 0.1 x 1.0 mm spot focus filaments, operated at 50 kV and 24 mA.  The x-ray beam is focused to a point by means of a Montel optic and collimated by an assembly of three pinholes. In the standard “high flux” configuration these are: (1) 0.75 mm diameter (2) beam defining 0.4 mm diameter (3) 1.0 mm, with spacing (1-to-2) 925 mm (2-to-3) 485 mm. The beam path from the first pinhole to the detector, including the sample space, is under vacuum (approx. 0.1 millibar).  The matching beam-stop is 4.31 mm diameter.  A set of “high resolution” pinholes is available: (1) 0.5 mm di-ameter (2) beam defining 0.15 mm diameter (3) 0.5 mm. They are installed at the same positions in the beam path as the “high flux” pinholes (above). The corre-sponding beam-stop is approx. 0.3 mm in diameter.  

The SAXS detector is a multi-wire proportional counter (Bruker Hi-Star) with 1024 x 1024 pixels and a beryllium front window 11.5 cm across.  The detector can be placed approximately 105 cm or 65 cm from the sample, allowing measurement of scattering angles from ca. 0.2 to 2.8 degrees (2-theta) or 0.2 to 4.8 degrees, re-spectively. Assuming a wavelength that is a weighted average of Cu-Kalpha1 and Cu-Kalpha2, this corresponds to q ranges in reciprocal Angstroms of approx. 0.14 to 0.2 or 0.14 to 0.34. Flood-field and spatial calibrations use an 55Fe source, dis-tance and centering calibration use x-ray scattering from silver behenate.

The WAXS detector is an image plate (Fuji FLA-7000 system) approximately 20 x 25 cm in size. To allow simultaneous SAXS/WAXs measurements, the image plate has a central hole that allows scattered radiation to pass through, filling the SAXS detector (at the 105 cm distance).  Distance and centering calibrations for the im-age plate use x-ray scattering from corundum (Al2O3).

Equipment Rates & Fees
  RPI Users External Nonprofit External Industry External Industry Partners
Standard $59 $97 $194 $175
Assisted $117.60 $193 $387 $348
Training $69 $114 $227 $204
  RPI Users External Nonprofit External Industry External Industry Partners
Personnel Time $60 $99 $197 $178

Valid through July 31, 2022. Rates are hourly unless specified otherwise and are subject to change without further notice.

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  • Equipment: If you used Core Facility equipment, please note this in the Materials and Methods. e.g., Thermogravimetric analysis was carried out using a TA Instruments TGA-Q50 (Rensselaer CBIS Analytical Biochemistry Core Facility).
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