• small-angle X-ray scattering;
  • window materials;
  • vacuum cameras;
  • synchrotron radiation

The intrinsic scattering from eight window materials commonly used at synchrotron facilities has been evaluated in the range 0.07 < q < 4 nm−1 by the use of a vacuum camera. Poly(oxydiphenylene-pyromellitimide) film, a polyimide film widely used as a window material for vacuum chambers, gave rise to two peaks at q = 0.8 and 4 nm−1. Poly(ether-ether-ketone) gave no Bragg peaks, although the background scattering was relatively high over the entire q range. When natural mica, synthetic mica, quartz glass, beryllium, silicon nitride and silicon carbide were compared, synthetic mica showed the lowest scattering in the range 0.6 < q < 5 nm−1, indicating that it is the most suitable window material for this q range.