Reducing Background Scatter and Maximizing Diffraction Signal to Noise

Methods to minimize the diffuse background and maximize your diffraction signal to noise

The diffuse background intensity in a diffraction pattern comes from many sources, both inside and outside the crystal, including:

  • Internal and external solvent.
  • Thermal motions of the protein and hydration water (thermal diffuse scatter).
  • Static crystal disorder (e.g., associated with flexible loop regions or poor packing).
  • The mount holding the crystal.
  • Air along the beam path between source and detector.

How can you minimize the diffuse background and maximize your diffraction signal to noise?

  • Use MicroMounts™ and/or our other sample mounting products in standard (not Dual) thickness to obtain the lowest possible scatter from your mount.
  • Minimize the amount of liquid around your crystal. Use a mount with an aperture that’s a bit smaller than the crystal, and carefully remove excess liquid using a paper wick or by gently tapping on the steel rod of the mount.
  • Use an X-ray beam that is smaller than your sample, to minimize the amount of scatter from surrounding liquid and the mount.
  • Orient your crystal on the mount to minimize data collection at angles that place the plane of the mount along (instead of perpendicular to) the X-ray beam.
  • Flash cool your crystal and collect data at T=100 K.
  • Dehydrate the crystal to reduce diffuse scatter from internal water, using the MicroRT™ system.
  • Use a larger crystal to maximize the ratio of sample volume to liquid, mount and air volume within the X-ray beam.
  • Use a helium filled bag or chamber to reduce scatter in the gas along the beam path.


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