While powder X-ray diffraction works excellently for particles of sizes larger than 10 nm, smaller particles only produce broad “amorphous” humps in the diffraction pattern. Still, “amorphous” is not quite the correct description for these particles, since they simply do not have enough long-range order for standard PXRD. Employing the powder pair distribution function (PDF) method (also called the total scattering method), such nano particles can be analyzed as well as polymers, liquids, glasses and other materials featuring only short-range order. The PDF method treats the information originating from diffuse peaks or background in a diffraction pattern, thus adding crucial information to the average Bragg diffraction data. PDF plots are displayed as G(r) versus r, where G(r) is the probability and r (in Å) is the radial distance between two atoms in the structure.

The STOE STADI P equipped with a Ag source and a Dectris multi Mythen detector is the perfect platform for PDF research. 

• Fast measurements – Four MYTHEN2 1K on one detector arm
• High Q_max – Ag anode (22 keV; 0.56 Å), 2θ_max =132° (Q = 20.5 Å^-1)
• Low air scattering – long collimator and fans in front of detectors, optimized beamstop position
• Low intrinsinc background – high detector quality: Hybrid Photon Counting MYTHEN2 R 1K detectors
• Good Q-resolution – Ge(111) monochromator for Kα₁, 50 µm strips