  We demonstrate the feasibility of obtaining accurate pair distribution
functions of thin amorphous films down to 80 nm, using modern laboratory-based
x-ray sources. The pair distribution functions are obtained using a single
diffraction scan (one-shot) without the requirement of additional scans of the
substrate or of the air. By using a crystalline substrate combined with an
oblique scattering geometry, most of the Bragg scattering of the substrate is
avoided, rendering the substrate Compton scattering the primary contribution.
By utilizing a discriminating energy filter, available in the latest generation
of modern detectors, we demonstrate that the Compton intensity can further be
reduced to negligible levels at higher wavevector values. We minimize
scattering from the sample holder and the air by the systematic selection of
pixels in the detector image based on the projected detection footprint of the
sample and the use of a 3D printed sample holder. Finally, x-ray optical
effects in the absorption factors and the ratios between the Compton intensity
of the substrate and film are taken into account by using a theoretical tool
that simulates the electric field inside the film and the substrate, which aids
in planning both the sample design and measurement protocol.
